Liquid crystal display and method of fabricating the same

ABSTRACT

An object of the present invention is to provide a liquid crystal display, which can surely perform an instillation process used when liquid crystal is sealed between substrates in a cell process, and a fabrication method thereof. A liquid crystal display comprises a sealing material made of a photo-curing type material which seals liquid crystal sandwiched between substrates, and a shading film having a shading area which overlays a red-colored layer transmitting red light, a green-colored layer transmitting green light and a blue-colored layer transmitting blue light, wherein only the blue-colored layer is formed in an area of the shading film contacting with the sealing material and the photo-curing type material of the sealing material is structured to have a light reactive area for a wavelength of blue color band.

This is a divisional of application Ser. No. 11/524,792, filed Sep. 21,2006, which is a divisional of application Ser. No. 11/397,274, filedApr. 4, 2006, which is a divisional of application Ser. No. 10/151,504which is now U.S. Pat. No. 7,199,855, filed May 20, 2002, which is adivisional of application Ser. No. 09/577,032 which is now U.S. Pat. No.7,230,669, filed May 23, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) and afabrication method thereof. Particularly, the present invention relatesto the liquid crystal display in which liquid crystal is sealed betweentwo panels by using an instilling method and the fabrication thereof.

2. Description of the Related Art

A liquid crystal display panel of a conventional liquid crystal displayis described with reference to FIG. 104. FIG. 104 shows a part of anupper surface of an active matrix-type liquid crystal display panelusing a TFT (thin film transistor) as a switching element viewed from acolor filter substrate side. As shown in FIG. 104, on a liquid crystaldisplay panel 1100, a plurality of pixel areas 1114 arranged in a matrixshape are formed on an array substrate 1116 side, and a TFT 1112 isformed in each pixel area 1114. A display area 1110 is structured by theplurality of the pixel areas 1114. It will be noted that although adetailed illustration is omitted, a gate electrode of a TFT 1112 in eachpixel area 1114 is connected to a gate wiring and a drain electrode isconnected to a data wiring respectively. Further, a source electrode ofthe TFT 1112 is connected to a pixel electrode formed in the pixel area1114. A plurality of the data wirings and the gate wirings are connectedto a terminal portion 1102 formed in the external periphery of the arraysubstrate 1116 so that the plurality of the data wirings and the gatewirings are connected to a driving circuit (not shown in the diagram)provided externally.

A color filter (CF) substrate 1104 formed smaller than the arraysubstrate 1116 by approximately the area of the terminal portion 1102 isprovided facing the array substrate 1116 while sealing liquid crystal ata predetermined cell gap. On the CF substrate 1104, a common electrode(not shown in the diagram) is formed and at the same time, BM (blackmatrix: shading film) 1080, 1180 and the like using color filters (shownby letters R(red), G(green) and B(blue) in the diagram), a Cr (chrome)film or the like are formed. Since a BM 1118 demarcates the plurality ofthe pixel area 1114 in the display area 1110 and earns contrast, the BM1118 is used for preventing a light leakage from occurring by shadingthe TFT 1112. Further, a BM picture-frame portion 1108 is provided forshading undesired light from outside the display area 1110.

The array substrate 1116 and the CF substrate 1104 are attached by asealing material 1106 made of photo-curing type resin.

Incidentally, a fabrication process of the liquid crystal display isroughly classified into an array process in which a wiring pattern, aswitching element (in a case of active matrix type) and the like areformed, a cell process in which an alignment layer treatment isperformed, spacers are arranged and liquid crystal is sealed betweenopposing glass substrates, and a module process in which an installationof a driver IC, attachment of a back light and the like are performed.In a liquid crystal injection process performed in the cell processamong the above processes, a method (vacuum injection method) is used,for example, in which the array substrate 1116 forming the TFT 1112 andthe opposite color filter substrate (opposite substrate) 1104 areattached with a use of the sealing material 1106, the sealing materialis cured, then liquid crystal and the substrates are placed in a vacuumchamber, an injection opening opened in the sealing material is immersedin liquid crystal, the inside of the chamber is returned to theatmospheric pressure, thereby sealing the liquid crystal between thesubstrates.

On the other hand, in recent years, an instilling method is drawingattention, in which, for example, a constant amount of liquid crystal isdropped on the substrate surface inside the frame of the sealingmaterial 1106 formed inside a frame shape in the periphery of the arraysubstrate, the array substrate 1116 and the CF substrate 1104 areattached in a vacuum and sealing of liquid crystal is performed.

A fabrication process of the liquid crystal display panel according tothe instilling method is briefly described with reference to FIGS. 108 athrough 108 c. First, as shown in FIG. 108 a, for example, liquidcrystal 1206 is dropped from a liquid crystal instilling equipment whichis not shown in the diagram at a plurality of positions on an arraysubstrate 1204 forming switching elements such as TFT and the like.Next, a common electrode and a color filter are formed in a displayarea, and an opposite substrate 1200 coated with a UV sealing material1202 to be cured by ultraviolet (UV) irradiation in the externalperiphery of a display area is aligned and attached to the arraysubstrate 1204. This process is performed in a vacuum. Then, when theattached substrates are returned to the atmospheric pressure as shown inFIG. 108 b, the liquid crystal 1206 between the attached array substrate1204 and the opposite substrate 1200 is spread due to the atmosphericpressure. Next, as shown in FIG. 108 c, while a UV light source 1208travels in a travel direction 1211 along the area the sealing material1202 is coated, UV light is irradiated to the sealing material 1202 andthe sealing material 1202 is cured.

In comparison to the vacuum injection method widely used for panelfabrication in the past, this instilling method has possibilities toreduce costs of fabricating a panel and to improve mass productivityowing to first, substantial reduction in the amount of liquid crystal tobe used and second, reduction in time to inject liquid crystal and thelike, therefore application of this instilling method is stronglydesired in the panel fabrication process.

For example, in the Japanese Lain-open Patent Application No. 63-179323,a method is recorded in which an accurately measured required amount ofliquid crystal is mounted on a substrate surface inside a sealingmaterial provided on one substrate, the opposite other substrate isoverlaid so that the substrate contacts with an upper surface of thesealing material before the liquid crystal spreads on the firstsubstrate surface and reaches an end face of the peripheral sealingmaterial, then both substrates are pressed in a decompressedenvironment, and the sealing material is cured.

However, in the above method, although basic processes of instillationto follow is shown, a specific description relative to a fabricationtechnology is insufficient and in reality, technical problems remain inpractical application of the process. The instilling process, incomparison to the liquid crystal injection process performed in thepast, enables to simply fabricate a liquid crystal panel at low cost butat the same time has technical difficulties as shown below resulting indelay in adopting the instilling method in a fabrication method of aliquid crystal display.

(1) Curing Defects of Sealing Material:

If uncured components of the sealing materials 1106 and 1202 makecontact with liquid crystal for a long period of time or are exposed inhigh temperature while contacting with liquid crystal, the liquidcrystal is contaminated. Therefore, photo-curing-type resin which israpidly cured by ultraviolet light irradiation is used for the sealingmaterials 1106 and 1202 when the instilling method is used.

Incidentally, the width of a picture-frame portion in the periphery of apanel is becoming narrow due to recent enlargement of the liquid crystalpanel 1100 and the like. Therefore, the sealing material 1106 formed ina frame shape in the periphery of a substrate is formed in many cases inthe very close proximity to the end of an external periphery of the BMpicture-frame portion shown in FIG. 104. Accordingly, when the arraysubstrate 1116 and the CF substrate 1104 are pressed and the area(hatched area in FIG. 104) where the sealing material 1106 and the BMpicture-frame portion 1108 make contact is generated, the area of thesealing material 1106 where the BM picture-frame portion 1108 contactsis shaded and not irradiated by light resulting in generating a curingdefect area in the said area.

(2) Seal Peeling:

FIGS. 105 a and 105 b show liquid crystal instillations in the cellprocess of a liquid crystal panel in the past. FIG. 105 a shows a statewhen liquid crystal (shown by a mark ◯) 1144 is dropped in equalintervals (in this example, matrix shape of three rows and four columns)in a similar shape to the frame shape of the sealing material 1106 on anupper surface of the array substrate inside the sealing material 1106.With respect to a dropping position of each liquid crystal 1144, thedistance to a dropping position of an adjacent liquid crystal 1144 has arelation, as shown in the diagram, which is d2=d4=d6=d8>d1=d3=d5=d7.FIG. 105 b shows a state in which the liquid crystal 1144 spreads afterthe array substrate and the CF substrate are attached. As shown in FIG.105 b, while the sealing material 1106 is formed in a rectangular frameshape, fluid drops of the dropped liquid crystal 1144 spread in acircular shape 1146 on the substrate surface. In a conventional droppingmethod, since fluid drops interfere with one another, approximately 20minutes of time is required to sufficiently lessen a space 1145 andcomplete spreading liquid crystal.

Thus, in the conventional method, a long period of time is required tospread liquid crystal to corner portions of the sealing material 1106and a waiting period for curing the sealing material is long.Accordingly, due to a difference in pressures between the inside andoutside of both substrates, possibilities of occurring peeling of cornerportions of the sealing material during the waiting period andgenerating liquid crystal leakage are high.

(3) Substrate Deformation and Display Irregularities:

Substrate holding in liquid crystal instillation in the conventionalprocess is performed by using vacuum chucks, electrostatic chucks or amechanical retainer. In the substrate holding by vacuum chucks, asubstrate is mounted on an attracting surface on a parallel surfaceplate and is fixed by vacuum-absorbing a back surface of a substrate. Bythis holding method, for example, an array substrate is held and anadequate amount of liquid crystal is dropped on an array substratesurface inside the frame shape of a sealing material by a dispenser andthe like. Then, a CF substrate is positioned in the vacuum environmentand entered into a process to be attached with an array substrate.However, since vacuum chucks do not function when a degree of vacuumincreases to a certain point when the substrates are held by vacuumchucks, the degree of vacuum at the time of attaching substrates can notbe sufficiently increased. Therefore, sufficient pressure for attachingboth substrates can not be coated and evenly attaching both substratesis difficult.

Further, in a mechanical holding, since stress is applied only to theholding side portion of a substrate, deformations such as a curvature,deflection and the like occur in a substrate, and both substrates cannot be held in parallel when attaching substrates after liquid crystalinstillation. If the attachment is performed when both substrates aredeformed, a displacement becomes large and problems of reduction inopening ratio of each electrode and light leakage from a shaded portionoccur.

FIGS. 106 a and 106 b are diagrams describing substrate attachment byelectrostatic chucks. FIG. 106 a shows a plan view of anelectrostatically attracted glass substrate 700 of the array substrate1116 in two-piece structure as an example. FIG. 106 b shows a crosssection cut by a line A-A in FIG. 106 a when the array substrate 1116and the CF substrate 1104 are to be attached.

As shown in FIGS. 106 a and 106 b, the areas to become two pieces ofarray substrate 1116 on the glass substrate 700 are electricallyisolated from each other. Electrostatic chucks for electricallyattracting the glass substrate 700 has four electrodes 740, 750, 760 and770 on a parallel surface plate. The electrodes 740 and 750 among thefour electrodes 740 through 770 structure positive electrodes and theelectrodes 760 and 770 structure negative electrodes. One surface of thearray substrate 1116 is electrostatically attracted by the positiveelectrode 740 and the negative electrode 760 and the other surface ofthe array substrate 1116 is electrostatically attracted by the positiveelectrode 750 and the negative 770. Space 680 is provided in a boundarybetween the positive electrode 740 and the negative electrode 760 and ina boundary between the positive electrode 750 and the negative electrode770. Although an illustration by a plan view is omitted, theelectrostatic chucks on a glass substrate 720 forming the CF substrate1104 has a similar structure to the electrostatic chucks attracting theglass substrate 700.

By mounting the glass substrate forming a conductive film on theelectrostatic chucks in such structure, applying voltage between theelectrode and the conductive film and generating the coulomb's forcebetween the glass and the conductive film, the glass substrate can beattracted. In the case of FIGS. 106 a and 106 b, the conductive film onthe glass substrate 700 includes the pixel electrodes, gate wirings,data wirings and the like formed on the array substrate 1116 area.Further, the conductive film on the glass substrate 720 forming the CFsubstrate area includes the common electrode and the like.

In order to attach substrates while holding the glass substrates 700 and720 by such electrostatic chucks, the positive poles 740 and 750 arecontacted to one of the two substantially equally divided areas of thearray substrate 1116, the negative poles 760 and 770 are contacted tothe remaining area, a predetermined voltage is applied between thepositive and negative poles and the glass substrate 700 iselectrostatically attracted. At this time, as shown in FIG. 106 b, asurface corresponding to the positive poles 740 and 750 in the arraysubstrate 1116 area of the glass substrate 700 is charged with negative(−) electricity and a surface corresponding to the negative poles 760and 770 are charged with positive (+) electricity. Thus, on theconductive film of the array substrate 1116 corresponding to the air gap680 of the boundary between the positive and negative poles, a boundarybetween a positive electric charge and a negative electric charge isformed.

Incidentally, an alignment film is formed on an upper portion of theconductive film of the array substrate 1116 and liquid crystal isdropped on the alignment film by instillation. Therefore, if the arraysubstrate 1116 area is electrostatically attracted according to theabove method, impure ion in liquid crystal is selectively attracted onthe alignment film at both sides of the boundary dividing the surface ofthe array substrate 1116 area into substantially two equal parts.Accordingly, the above method has a problem of generating displayirregularities in which when a formed liquid crystal panel is displayed,the brightness in the two surfaces sandwiching the said boundary varies.

Further, when the glass substrate 700 forming the array substrate 1116and the glass substrate 720 forming the CF substrate 1104 are attachedwhile being held by electrostatic attraction, if voltage in reversedpolarity of positive or negative is applied on the opposing surfaces ofboth glass substrates 700 and 720 as shown in FIG. 106 b, the coulomb'sforce is operated to each of the opposing substrates resulting inreduction of the substrate holding strength due to electrostaticattraction. Thus, possibilities of causing a substrate deformation orcontacting the substrates with each other and causing electrostaticdestruction exist.

Furthermore, a method in which substrates are held by electrostaticchucks of which the substrate holding strength is not affected by thedegree of vacuum also has a problem in which a glow discharge occurs inthe course of decompressing the atmospheric pressure for attachingsubstrates and may generate damage to a circuit or a TFT element on asubstrate. Also, a phenomenon may occur in which an operation of theelectrostatic chucks becomes unstable due to the air remained betweenthe electrostatic chucks and the substrates, and the substrates breakoff from the electrostatic chucks in the course of the substrateattachment process.

(4) Variations in Cell Gap:

In order to evenly spread liquid crystal inside both substrates in theinstillation process, liquid crystal is required to be dropped atmultiple points on a substrate surface by dispenser or the like.However, since the amount of liquid crystal to be dropped per onesubstrate surface is minute, when dropping positions are scattered intomultiple points, an extremely small amount of liquid crystal must beaccurately dropped. Nevertheless, the amount of liquid crystal to bedropped varies due to variations in viscosity or volume of liquidcrystal affected by changes in the environment such as temperaturevariations at the time of instillation or variations in quality of adispenser. As a result, variations in cell gap between both substratesoccur.

FIGS. 107 a to 107 c are cross sections cut vertical to a liquid crystalpanel surface and shows an example of variations in cell gap. FIG. 107 ashows a state in which a desired cell gap is obtained by an ideal liquidcrystal instillation. In FIGS. 107 a to 107 c, the array substrate 1116and the CF substrate 1104 are attached by the sealing material 1106 anda predetermined cell gap is secured by beads 1150 as spacers. However,if the amount of dropped liquid crystal increases, as shown in FIG. 107b, the sealing material 1106 can not be pressed to an intended gap dueto excessive liquid crystal resulting in a problem in which displayirregularities occur in the peripheral portion of a panel (periphery ofpicture-frame portion). When the amount of dropped liquid crystal isfurther increased, as shown in FIG. 107 c, a phenomenon in which acenter portion of a panel is expanded due to the sealing material 1106causing a press defect occurs resulting in display irregularities on awhole surface.

(5) Degradation of Liquid Crystal:

Further, in a liquid crystal display fabricated by using the instillingmethod, a problem is generated in which display irregularities occur atthe edge of a seal where a sealing material and liquid crystal contact.One of the causes is described with reference to FIG. 109. FIG. 109shows a partial cross section of the end portion of a liquid crystaldisplay panel. An array substrate 1200 and an opposite substrate 1204face each other through the aid of a sealing material 1202. A pixelelectrode and a bus line (in FIG. 109, these are collectively referredby a code 1212) are formed on the array substrate 1200 surface facingthe opposite substrate 1204, an alignment film 1214 is formed on thesurface 1212, a common electrode and a color filter (in FIG. 109, theseare collectively referred by a code 1216) are formed on the oppositesubstrate 1204 surface facing the array substrate 1200, and an alignmentfilm 1218 is formed on the surface 1216. A predetermined cell gap iskept and the liquid crystal 1206 is sealed between the opposingelectrodes. As shown in the diagram, the liquid crystal 1206 at the endportion of a panel contacts with the sealing material 1202.

If UV irradiation is performed toward the sealing material 1202 forcuring the sealing material in such a structure, UV light is slightlydispersed and a liquid crystal 1220 in a hatched area shown in thediagram adjacent to the sealing material 1202 is also irradiated.However, usually, if a liquid crystal material is irradiated by UVlight, characteristics of liquid crystal are degraded, and specifically,resistivity tends to be reduced and high voltage retention ratiorequired in TFT-LCD and the like can not be kept. Therefore, operatingvoltage of a liquid crystal cell is different in comparison with aportion which is not irradiated by UV, display irregularities athalf-tone display become prominent.

Further, since an area where the sealing material 1202 before UVirradiation and the liquid crystal 1206 make contact is large in aninstilling method, the possibility of contaminating a liquid crystalmaterial due to uncured sealing material is high. In order to suppressthis liquid crystal contamination, a UV sealing material is required tobe rapidly cured by instantly performing UV irradiation. However, thereis a problem in which if a UV light high in strength is irradiated inorder to reduce irradiation time, damage caused by the light leakage tothe liquid crystal material also becomes large.

As described above, photo-curing resin or heat-curing resin is used fora sealing material in the instilling method. As preceding technologiesrelative to photo-curing a sealing material, a technique in whichultraviolet light is irradiated through a mask having a predeterminedpattern transmitting light to attached substrates (Japanese Laid-openPatent Application No. 09-61829), a technique in which an upper andlower substrates are arranged facing each other so that a shaded portionis not overlapped with a position a seal is arranged (Japanese Laid-openPatent Application No. 09-90383), a technique in which a panel ispressed by a pressure difference between the pressure at the time ofattachment of substrates and the atmospheric pressure or the pressure ina vacuum chamber after the attachment (Japanese Laid-open PatentApplication No. 10-26763) and the like are known.

However, even if these techniques are used, the photo-curing process inthe instilling method holds problems described below.

First, photo-degradation of liquid crystal can be cited. Althoughultraviolet-light-curing resin is used for photo-curing resin because ofthe preservation ability and the adhesive strength as previouslydescribed, when ultraviolet light is irradiated to liquid crystal,photolysis reaction makes progress and an ion impurity is generated.This ion impurity causes display defects such as irregularities due to areduction in voltage retention ratio or in image persistence. For thisreason, a use of a mask having a predetermined pattern transmittinglight as disclosed in the above document (Japanese Laid-open PatentApplication No. 09-61829) is conceivable. However, this method of usinga mask has a problem in which since a mask is required for each sealpattern and the number of processes is increased by a mask alignmentprocess, the goal of the instilling method of liquid crystal such asreducing a fabrication cost of a panel and improving mass productivitymay be rather prevented than accomplished.

Secondly, enlargement of an outside dimension of a panel can be cited.Usually a terminal made of many metal films is formed in a non-displayarea on the array substrate side. In order to arrange an upper and lowersubstrates facing each other so that a shading portion of the substratesdo not overlap with a position a sealing material is arranged asdescribed in the above document (Japanese Laid-open Patent ApplicationNo. 09-90383), essentially, a seal is required to be formed outside thepicture frame of a black matrix, thereby resulting in enlargement of anoutside dimension of a panel.

Thirdly, there is a problem of displacement. Since curing of a seal isinstantly performed in photo-curing, the stress due to a waviness andcurvature which are natural characteristics of a substrate tend to stay.If a heat treatment is performed in this state, the stress is releasedand a displacement of a substrate occurs.

Fourthly, there is a problem of press defect. In instillation, a wholesubstrate is pressurized by a pressure difference between the pressureat the time of attaching substrates and the atmospheric pressure or thepressure in a vacuum chamber after the attachment as described in theabove document (Japanese Laid-open Patent Application No. 10-26763) tospread liquid crystal. Immediately after pressurization, since liquidcrystal does not yet reach a sealing material, the sealing material isinstantly pushed and pressed to the thickness of a spacer insertedbetween substrates. However, since the inside of the panel is thickerthan a predetermined thickness, the sealing material is subsequentlypushed back. Although the thickness of the panel gradually approachesthe predetermined thickness and the sealing material is again pressed tothe thickness of a spacer by extending shelf time, liquid crystal iscontaminated from uncured sealing material in the time the liquidcrystal is left. Therefore, as a matter of fact, curing is required tobe performed in the least amount of time. Due to this balance,sufficient shelf time can not be taken and insufficient shelf timebecomes a cause of generating press defect.

In the above vacuum injection method or instilling method, in order tocure a sealing material in a short period of time, photo-curing resin orphoto plus heat-curing resin is used for a seal. However, in theinstilling method, there is a possibility in which a sealing materialcontacts with liquid crystal when the sealing material is uncured. If asealing material component elutes into liquid crystal or ultravioletlight is irradiated to adjacent liquid crystal when a sealing materialis cured and liquid crystal is resolved by photolysis, the voltageretention ratio of liquid crystal at the edge of a seal is reduced,thereby occurring display irregularities.

In order to deal with this problem, for example, in the JapaneseLaid-open Patent Application No. 06-194615, a liquid crystal display inwhich a column-shape spacer is arranged outside the pixel area on eitherone of a pair of substrates and a frame-shape spacer (frame-shapestructure) is arranged along the fringe periphery of the said substrateis disclosed. These spacers are simultaneously formed in aphotolithography process and are used to fabricate a liquid crystalpanel using an instilling method.

FIG. 110 a shows a part of an upper surface of a conventionalactive-matrix type liquid crystal panel 1100 different from the oneusing a TFT as a switching element shown in FIG. 104 viewed from a CF(color filter) substrate side. FIG. 110 b shows a partial cross sectioncut at a line A-A of FIG. 110 a. A plurality of pixel areas 1114arranged in a matrix shape are formed on an array substrate 1116 side ofthe liquid crystal display panel 1100 and a TFT (not shown in thediagram) is formed in each pixel area 1114. A picture display area 1110is formed by a plurality of pixel areas 1114.

A CF substrate 1104 is formed smaller than the array substrate 1116 byapproximately the width of a terminal portion 1102 and arranged facingthe array substrate 1116 while sealing a liquid crystal at apredetermined cell gap. The array substrate 1116 and the CF substrate1104 are attached by a main seal 1106 made of photo-curing type resin. Awidth 1106′ shown by double dotted lines indicates the width of the mainseal 1106 at the time of coating. A frame-shape structure 1111separating the main seal 1106 and the liquid crystal 22 is formed in thearea between the main seal 1106 and the display area 1110. The liquidcrystal 22 is sealed in the area surrounded by the frame-shape structure1111 between the array substrate 1116 and the CF substrate 1104.

A common electrode (not shown in the diagram) and color filters(indicated by letters R(red), G(green), B(blue) in the diagram) areprovided on the CP substrate 1104. A BM picture frame 1108 and a BMdeciding the space between pixel areas are also formed on the CFsubstrate 1104. An external peripheral end of the frame-shape structure1111 is arranged inside an external peripheral end of the BM pictureframe viewed from a direction vertical to the surface of the substrate1116. Therefore, a peripheral end portion inside the main seal 1106overlaps with a peripheral end portion outside the BM picture frame 1108and an area 1107 is formed. Thus, UV light is shaded by the BM pictureframe 1108 and a curing defect of the main seal 1106 is generated in thearea 1107.

Further, as shown in FIG. 111, if the frame-shape spacer 1111 equivalentto a cell gap alone is provided in the fringe periphery of the CFsubstrate 1104 when liquid crystal more than the amount to fill theframe-shape spacer 1111 at instillation is dropped, excess liquidcrystal flows over the frame-shape spacer 1111, uncured sealing material1106 and the liquid crystal 22 make contact, thereby dispersingcontaminant. Furthermore, as shown in FIG. 112, if a cell gap is thick,the liquid crystal 22 easily flows over the frame-shape spacer 1111before the liquid crystal 22 is completely spread. FIG. 112 shows astate in which a surface of the array substrate 1116 is viewed from theCF substrate 1104 side. When the liquid crystal 22 is dropped at aplurality of liquid crystal dropping points by using a liquid crystalinstilling method, and the substrates 1116 and 1104 are attached, aboundary 1123 of the liquid crystal 22 at the time of attachment isgradually spread. Before the liquid crystal 22 is completely spread, anuninjected portion of liquid crystal 1121 is formed, and even if thereis no excess liquid crystal, since the cell gap is higher than theheight of the frame-shape spacer 1111, the liquid crystal boundary 1123flows over the frame-shape spacer 1111 and, for example, at a position1122, contacts with uncured main seal 1106. Also, as shown in FIG. 113,since the atmospheric pressure evenly operates on the whole substratesurface when the substrates are returned in an atmosphere afterattachment, the center of the substrate becomes depressed with respectto the main seal 1116 in which the resistance is larger. As a result,the frame-shape spacer 1111 is lifted up and the liquid crystal 22contacts with the main seal 1106.

In addition to the problems described above, the conventional instillingmethod further holds problems identified below.

(6). Seal Peeling Due to a Curing Defect:

A black matrix (BM: shading film) is usually formed in the fringeperiphery portion (picture frame) of a liquid crystal display substrate.Unless a frame-shape spacer is strategically arranged, when a sealingmaterial is spread after substrates are attached, a part of the sealingmaterial overlaps with the end of a BM picture frame and UV light isobstructed, thereby resulting in curing defects. Since adhesive strengthis weak in the portion of a curing defect, external stress isconcentrated and peeling of a sealing material is induced. If a positionof a sealing material is sufficiently apart from the end of a BM pictureframe, such defects do not occur. However, by so doing, thepicture-frame area is enlarged and the glass substrate surface can notbe efficiently utilized.

(7) Excess Liquid Crystal Flowing Over a Frame-Shape Spacer:

If a column-shape spacer equivalent to a cell gap alone is provided in afringe periphery of a substrate, when liquid crystal more than theamount to fill the frame-shape spacer is dropped at the time ofinstillation, an excess liquid crystal flows over the frame-shapespacer, uncured sealing material and liquid crystal contact, therebydispersing contaminant. Further, when there are variations in a droppingamount from a dropping dispenser even if the dropping of liquid crystalis controlled, or when liquid crystal reaches the frame-shape spacerbefore liquid crystal fully fills inside the frame, since a cell gap isthick before liquid crystal is completely spread, liquid crystal easilyflows over the frame-shape spacer.

(8) Irregularities Due to a Dropping Mark:

A liquid crystal display fabricated by an instilling method has aproblem in which a “dropping mark” in the area liquid crystal is droppedis seen as an irregularity. FIGS. 114 a through 114 c show an example ofthe “dropping mark”. FIG. 114 c shows a liquid crystal instillation in astate in which a dropped liquid crystal 136 is adhered on an alignmentfilm 134 on a substrate 132. In display irregularities due to “droppingmarks”, there are irregularities 130 as shown in FIG. 114 a in whichboundaries of the dropped areas are visible and surface irregularities131 as shown in FIG. 114 b in which the brightness of the whole droppedareas is different from the brightness of the periphery. After droppedliquid crystal and an alignment film contacts, an instilled panel ispositioned and attached, and then liquid crystal is spread in a vacuum.

The cause of the “dropping mark” is considered to be a contact betweenliquid crystal and an alignment film in the atmospheric pressure.Further, a degree of the “dropping mark” is found to be differentdepending on a liquid crystal material for dropping and a material foran alignment film. If a liquid crystal material has strong polarity anda material for liquid crystal and a material used for an alignment filmmaterial are inferior in electrical characteristics (i.e. low voltageretention ratio, high ion density, large residual DC voltage), the“dropping mark” tends to be more visibly generated. Specifically,although in a liquid crystal panel in which alignment control of liquidcrystal of MVA-(multi-domain vertical alignment) mode can be realized,N-type (negative dielectric anisotropy: Δε<0) liquid crystal materialand a vertical alignment film are required, material selection for thesematerials is limited in comparison with P-type liquid crystal materialand a horizontal alignment film, and there are only few materials amongthe existing materials which satisfy requirements of electricalcharacteristics. Therefore, liquid crystal even more reliable isrequired to be used for a liquid crystal material which contacts with analignment film in the atmospheric pressure and a different fabricationmethod from before is required.

(9) Other Problems:

Furthermore, an instilling method has a problem in which administrationto prevent substrates failed at instillation due to troubles in theprocess and substrates failed to create a cell gap adjacent to a mainseal from advancing to subsequent processes is difficult. Specifically,since the birefringence of liquid crystal viewed from the front surfaceof a panel when voltage is not applies is equal to 0 in an MVA-modeliquid crystal panel, a liquid crystal layer is seen as the same as anair layer and grasping a state of liquid crystal instillation withcertainty is difficult. Therefore, easily and steadily performing aninspection of display irregularities of a liquid crystal panelfabricated according to an instilling method is desired.

Also, in order to reduce contamination of liquid crystal due to acontact between liquid crystal and uncured sealing material, a use of asealing material of high viscosity can be considered. However, a gap isdifficult to create by a sealing material of high viscosity and a cellgap at the edge of a seal becomes thicker then a cell gap at the centerof a display, thereby resulting in generating a problem of displayirregularities.

Further, upon performing an instilling method, due to variations in theenvironment during the period up to when a sealing material is cured byUV irradiation after attaching substrates in a vacuum and subsequentlyreturning the attached substrates in an atmosphere, changes in acondition of substrates at the time of UV irradiation, and a lack ofstability in positioning substrates when a gap is created or the like, adisplacement in attaching or a displacement from substrate distortion isgenerated, or a gap defect is generated, thereby resulting in a problemin which producing a stable product is difficult.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystaldisplay and a fabrication method thereof wherein liquid distillation cansurely be performed in a cell process.

The object is achieved by a liquid crystal display which comprises asealing material made of a photo-curing type material sealing liquidcrystal sandwiched between two substrates, a shading area overlaying ared-colored layer to transmit color light, a green-colored layer totransmit green light and blue-colored layer transmitting blue light,wherein only the blue-colored layer is formed in the shading areacontacting with the sealing material and the photo-curing type materialfor the sealing material has a light reactive area for a wavelength ofblue-color band.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are diagrams showing a schematic structure of a liquidcrystal display panel according to a first embodiment of the presentinvention.

FIG. 2 is a diagram showing a light transmission spectrum of ared-colored layer 28, green-colored layer 26 and blue-colored layer 24when a film thickness is equal to 1.3 nm.

FIG. 3 is a diagram showing a photo-absorption spectrum (β) of aphoto-curing-type resin of a sealing material 6 according to the firstembodiment of the present invention and a blue-color transmissionspectrum (γ) of the blue-colored layer 24 and further showing aphoto-absorption spectrum (α) of a conventional photo-curing-type resinfor comparison.

FIGS. 4 a and 4 b are diagrams describing an overlap of the sealingmaterial of a liquid crystal display according to a second embodiment ofthe present invention and a BM picture-frame portion.

FIGS. 5 a and 5 b are diagrams showing a comparison example with respectto the liquid crystal display shown in FIGS. 4 a and 4 b in the secondembodiment of the present invention.

FIG. 6 is a diagram describing a relation between the sealing materialfor corner portions of a liquid crystal display according to the secondembodiment of the present invention and a BM picture-frame portion.

FIG. 7 is a diagram showing a comparison example with respect to theliquid crystal display shown in FIG. 6 in the second embodiment of thepresent invention.

FIGS. 8 a and 8 b are diagrams describing a relation between a transferof a liquid crystal display according to a third embodiment of thepresent invention and a BM picture-frame portion.

FIG. 9 is a diagram showing a comparison example with respect to theliquid crystal display shown in FIGS. 5 a and 8 b according to the thirdembodiment of the present invention.

FIGS. 10 a and 10 b are diagrams describing a schematic structure of alight source for UV irradiation according to a fourth embodiment of thepresent invention.

FIG. 11 is a diagram showing a comparison example with respect to thelight source for UV irradiation shown in FIGS. 10 a and 10 b in thefourth embodiment of the present invention.

FIGS. 12 a and 12 b are diagrams showing a schematic structure of aliquid crystal display according to a fifth embodiment of the presentinvention.

FIGS. 13 a and 13 b are diagrams showing a schematic structure relativeto an example of a variation of the liquid crystal display according tothe fifth embodiment of the present invention.

FIGS. 14 a and 14 b are diagrams showing a schematic structure relativeto an example of an other variation of the liquid crystal displayaccording to the fifth embodiment of the present invention.

FIG. 15 is a diagram showing a UV spectrum of Comparison Example E andExample G in the liquid crystal display according to the fifthembodiment of the present invention.

FIG. 16 is a diagram describing a creation of a gap adjacent to aframe-shape structure 12 by pressuring the frame-shape structure 12 by apressure P before a liquid crystal boundary 23 of a liquid crystal 22reaches the frame-shape structure 12 in the liquid crystal displayaccording to the fifth embodiment of the present invention.

FIG. 17 is a diagram showing Example 1 in a liquid crystal display and afabrication method thereof according to a sixth embodiment of thepresent invention.

FIGS. 18 a and 18 b are diagrams showing Example 2 in the liquid crystaldisplay and the fabrication method of the liquid crystal displayaccording to the sixth embodiment of the present invention.

FIG. 19 is a diagram showing Example 3 in the liquid crystal display andthe fabrication method of the liquid crystal display according to thesixth embodiment of the present invention.

FIGS. 20 a and 20 b are diagrams showing Example 4 in the liquid crystaldisplay and the fabrication method of the liquid crystal displayaccording to the sixth embodiment of the present invention.

FIGS. 21 a and 21 b are diagrams showing Example 5 in the liquid crystaldisplay and the fabrication method of the liquid crystal displayaccording to the sixth embodiment of the present invention.

FIGS. 22 a and 22 b are diagrams showing Example 6 in the liquid crystaldisplay and the fabrication method of the liquid crystal displayaccording to the sixth embodiment of the present invention.

FIG. 23 is a diagram showing Example 7 in the liquid crystal display andthe fabrication method of the liquid crystal display according to thesixth embodiment of the present invention.

FIG. 24 is a diagram showing Example 8 in the liquid crystal display andthe fabrication method of the liquid crystal display according to thesixth embodiment of the present invention.

FIGS. 25 a and 25 b are diagrams describing a problem in the past in aseventh embodiment of the present invention.

FIG. 26 is a diagram describing other problem in the past in the seventhembodiment of the present invention.

FIGS. 27 a through 27 c are diagrams showing Example 1 in a liquidcrystal display and a fabrication method thereof according to theseventh embodiment of the present invention.

FIG. 28 is a diagram showing Example 2 in the liquid crystal display andthe fabrication method of the liquid crystal display according to theseventh embodiment of the present invention.

FIGS. 29 a and 29 b are diagrams showing Example 3 in the liquid crystaldisplay and the fabrication method of the liquid crystal displayaccording to the seventh embodiment of the present invention.

FIGS. 30 a and 30 b are diagrams showing Example 4 in the liquid crystaldisplay and the fabrication method of the liquid crystal displayaccording to the seventh embodiment of the present invention.

FIGS. 31 a through 31 c are diagrams showing Example 5 in the liquidcrystal display and the fabrication method of the liquid crystal displayaccording to the seventh embodiment of the present invention.

FIGS. 32 a and 32 b are diagrams showing a schematic structure of aliquid crystal display according to an eighth embodiment of the presentinvention.

FIGS. 33 a through 33 c are diagrams showing a structure of a lightreflection layer provided in the liquid crystal display according to theeighth embodiment of the present invention.

FIG. 34 is a diagram showing a structure of a light reflection layerprovided in a reflection-type liquid crystal display as an example of avariation of the eighth embodiment of the present invention.

FIG. 35 is a diagram describing an example of an irradiation method ofUV light according to the eighth embodiment of the present invention.

FIG. 36 is a diagram showing a partial horizontal cross section of anend portion of a liquid crystal display according to a ninth embodimentof the present invention.

FIG. 37 is a diagram showing characteristics of two kinds of liquidcrystal materials (A) and (B).

FIGS. 38 a through 38 c are diagrams describing a direction of apolarizing axis 46 in irradiation of a polarized UV according to theninth embodiment of the present invention.

FIGS. 39 a and 39 b are diagrams describing the direction of thepolarizing axis 46 in irradiation of the polarized UV according to theninth embodiment of the present invention.

FIG. 40 is a diagram of a partial horizontal cross section of an endportion of a liquid crystal display according to a tenth embodiment ofthe present invention and showing a state in which a liquid crystal 22of negative dielectric anisotropy is instilled and vertically aligned bya vertical alignment film.

FIGS. 41 a through 41 c are diagrams of a partial horizontal crosssection of the end portion of a liquid crystal display according to thetenth embodiment of the present invention and showing a state in which aliquid crystal 22 of positive dielectric anisotropy is instilled andvertically aligned by the vertical alignment film.

FIGS. 42 a and 42 b are diagrams of a partial horizontal cross sectionof the end portion of the liquid crystal display according to the tenthembodiment of the present invention and showing a state in which theliquid crystal 22 of positive dielectric anisotropy is instilled andvertically aligned by applying voltage to the liquid crystal 22.

FIGS. 43 a and 43 b are diagrams describing Example 4 in a liquidcrystal display according to an eleventh embodiment of the presentinvention.

FIG. 44 is a diagram describing Example 4 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 45 is a diagram describing Example 4 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 46 is a diagram describing Example 4 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIGS. 47 a and 47 b are diagrams describing Example 5 in the liquidcrystal display according to the eleventh embodiment of the presentinvention.

FIG. 48 is a diagram describing Example 5 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 49 is a diagram describing Example 6 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 50 is a diagram describing Example 7 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 51 is a diagram describing an example 8 in the liquid crystaldisplay according to the eleventh embodiment of the present invention.

FIG. 52 is a diagram describing Example 8 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 53 is a diagram describing Example 8 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 54 is a diagram describing Example 9 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIG. 55 is a diagram describing Example 10 in the liquid crystal displayaccording to the eleventh embodiment of the present invention.

FIGS. 56 a and 56 b are diagrams showing an instillation of liquidcrystal in a cell process of a liquid crystal panel according to atwelfth embodiment of the present invention.

FIG. 57 is a diagram briefly describing an instillation in a fabricationmethod of a liquid crystal display according to a thirteenth embodimentof the present invention.

FIG. 58 is a diagram briefly describing the instillation in thefabrication method of the liquid crystal display according to thethirteenth embodiment of the present invention.

FIG. 59 is a diagram briefly describing the instillation in thefabrication method of the liquid crystal display according to thethirteenth embodiment of the present invention.

FIG. 60 is a diagram showing an upper surface of a substrate 30 whereliquid crystal is dropped in the fabrication method of the liquidcrystal display according to the thirteenth embodiment of the presentinvention.

FIG. 61 is a diagram describing a dispersion state of dropped liquidcrystal in a fourteenth embodiment of the present invention.

FIG. 62 is a diagram showing a pixel formed in a liquid crystal displaypanel and a dispersion state of the liquid crystal which is dropped inthe pixel formed in the liquid crystal display panel in the fourteenthembodiment of the present invention.

FIG. 63 is a diagram showing a state in which an outline shape of afront end portion of dispersing liquid crystal is controlled to besubstantially a similar shape to a shape of a main seal 6 in the liquidcrystal display according to the fourteenth embodiment of the presentinvention.

FIG. 64 is a diagram showing a structure 29 for determining a cell gapin the liquid crystal display according to the fourteenth embodiment ofthe present invention.

FIG. 65 is a diagram showing structures 28 a and 28 b for controllingliquid crystal dispersion in the liquid crystal display according to thefourteenth embodiment of the present invention.

FIG. 66 is a diagram showing an example of arrangement of the structures28 a, 28 b and 29 in the liquid crystal display according to thefourteenth embodiment of the present invention.

FIGS. 67 a through 67 d are diagrams describing liquid crystalinstillation, a substrate attaching process and a substrate holdingoperation in the substrate attaching process in a liquid crystal displayaccording to a fifteenth embodiment of the present invention.

FIGS. 68 a and 68 b are diagrams describing substrate attachment with ause of electrostatic chucks in a liquid crystal display according to asixteenth embodiment of the present invention.

FIGS. 69 a and 69 b are diagrams describing substrate attachment with ause of electrostatic chucks in a liquid crystal display according to aseventeenth embodiment of the present invention.

FIGS. 70 a and 70 b are diagrams showing a comparison between aphoto-curing process in an instillation according to an eighteenthembodiment of the present invention and a photo-curing process in aconventional instillation.

FIG. 71 is a diagram showing a schematic structure of a substrateattachment equipment according to the eighteenth embodiment of thepresent invention.

FIG. 72 is a diagram briefly describing a fabrication method of a liquidcrystal display according to a nineteenth embodiment of the presentinvention.

FIG. 73 is a diagram briefly describing the fabrication method of theliquid crystal display according to the nineteenth embodiment of thepresent invention.

FIG. 74 is a diagram briefly describing the fabrication method of theliquid crystal display according to the nineteenth embodiment of thepresent invention.

FIG. 75 is a diagram briefly describing the fabrication method of theliquid crystal display according to the nineteenth embodiment of thepresent invention.

FIG. 76 is a diagram briefly describing the fabrication method of theliquid crystal display according to the nineteenth embodiment of thepresent invention.

FIGS. 77 a and 77 b are diagrams briefly describing the fabricationmethod of the liquid crystal display according to the nineteenthembodiment of the present invention.

FIG. 78 is a diagram briefly describing the fabrication method of theliquid crystal display according to the nineteenth embodiment of thepresent invention.

FIG. 79 is a diagram showing a fabrication method of a liquid crystaldisplay according to a twentieth embodiment of the present invention.

FIG. 80 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIG. 81 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIGS. 82 a and 82 b are diagrams showing the fabrication method of theliquid crystal display according to the twentieth embodiment of thepresent invention.

FIG. 83 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIG. 84 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIG. 85 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIG. 86 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIG. 87 is a diagram showing the fabrication method of the liquidcrystal display according to the twentieth embodiment of the presentinvention.

FIGS. 88 a and 88 b are diagrams describing substrate attachment in aliquid crystal display according to a twenty-first embodiment of thepresent invention.

FIG. 89 is a diagram describing substrate attachment in a liquid crystaldisplay according to a twenty-second embodiment of the presentinvention.

FIGS. 90 a through 90 c are diagrams describing a liquid crystal displayand a fabrication method thereof according to a twenty-third embodimentof the present invention.

FIG. 91 is a diagram showing a schematic structure of a substrate of aliquid crystal display according to a twenty-fourth embodiment of thepresent invention.

FIG. 92 is a diagram describing protruding portions 96 and 98 of theliquid crystal display according to the twenty-fourth embodiment of thepresent invention.

FIG. 93 is a diagram describing an example of a variation of theprotruding portions 96 and 98 of the liquid crystal display according tothe twenty-fourth embodiment of the present invention.

FIG. 94 is a diagram showing a liquid crystal instilling equipment usedto fabricate the liquid crystal display according to the twenty-fourthembodiment of the present invention.

FIG. 95 is a diagram showing the results of Example 1 in a fabricationmethod of a liquid crystal display according to a twenty-fifthembodiment of the present invention and a comparison example.

FIG. 96 is a diagram showing the result of Example 2 in the fabricationmethod of the liquid crystal display according to the twenty-fifthembodiment of the present invention.

FIG. 97 is a diagram showing the result of Example 2 in the fabricationmethod of the liquid crystal display according to the twenty-fifthembodiment of the present invention.

FIG. 98 is a diagram showing a pin 90 used in the fabrication method ofthe liquid crystal display according to the twenty-fifth embodiment ofthe present invention.

FIG. 99 is a diagram showing the result of Example 3 in the fabricationmethod of the liquid crystal display according to the twenty-fifthembodiment of the present invention.

FIG. 100 is a diagram showing the result of the examples in thefabrication method of the liquid crystal display according to thetwenty-fifth embodiment of the present invention.

FIG. 101 is a diagram showing a schematic structure of an activematrix-type liquid crystal display fabricated by a fabrication method ofa liquid crystal display according to a twenty-sixth embodiment of thepresent invention.

FIG. 102 is a diagram showing an example of a panel inspection in thefabrication method of the liquid crystal display according to thetwenty-sixth embodiment of the present invention.

FIG. 103 is a diagram showing the example of the panel inspection in thefabrication method of the liquid crystal display according to thetwenty-sixth embodiment of the present invention.

FIG. 104 is a diagram showing a schematic structure of a conventionalliquid crystal display panel.

FIGS. 105 a and 105 b are diagrams showing a liquid crystal instillationin a cell process of the conventional liquid crystal panel.

FIGS. 106 a and 106 b are diagrams describing substrate attachment byconventional electrostatic chucks.

FIGS. 107 a to 107 c are diagrams showing irregularities of a cell gapin the conventional liquid crystal panel.

FIGS. 108 a through 108 c are diagrams describing a fabrication processof a liquid crystal display panel according to an instilling method.

FIG. 109 is a diagram showing a partial horizontal cross section of anend portion of the conventional liquid crystal display panel.

FIGS. 110 a and 110 b are diagrams showing a schematic structure of aconventional liquid crystal display.

FIG. 111 is a diagram describing a problem in a fabrication method ofthe conventional liquid crystal display.

FIG. 112 is a diagram describing the problem in the fabrication methodof the conventional liquid crystal display.

FIG. 113 is a diagram describing the problem in the fabrication methodof the conventional liquid crystal display.

FIGS. 114 a, 114 b, and 114 c are diagrams describing the problem in thefabrication method of the conventional liquid crystal display.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A liquid crystal display and a fabrication method thereof according to afirst embodiment of the present invention is described with reference toFIG. 1 a through FIG. 3. In this embodiment, the liquid crystal displayand the fabrication method of the liquid crystal display reducing curingdefects of a sealing material and steadily performing instillation ofliquid crystal in a cell process are described. First, a schematicstructure of a liquid crystal panel of the liquid crystal displayaccording to this embodiment is described with reference to FIGS. 1 aand 1 b. FIG. 1 a shows a part of an upper surface of an active matrixtype liquid crystal panel 1 using a TFT as a switching element viewedfrom a CF substrate side. FIG. 1 b shows a partial cross section cut ata line A-A of FIG. 1 a. A plurality of pixel areas 14 arranged in amatrix shape are formed on an array substrate 16 side of the liquidcrystal panel 1 and a TFT 13 is formed in each of the pixel area 14.Further, as shown in FIGS. 1 a and 1 b, a picture display area 10 isstructured by the plurality of the pixel areas 14. Although detaileddiagrams are omitted, a gate electrode of the TFT 13 of each pixel area14 is connected to a gate wiring and a drain electrode is connected to adata wiring respectively. Furthermore, a source electrode of the TFT 13is connected to a pixel electrode formed in the pixel area 14. Aplurality of the data wirings and the gate wirings are connected to aterminal portion 2 formed in an external periphery of the arraysubstrate 16 to be connected to a driving circuit (not shown in thediagram) provided outside.

A CF substrate 4 formed smaller than the array substrate 16 byapproximately the width of the terminal portion 2 seals liquid crystalat a predetermined cell gap and is arranged opposing the array substrate16. The array substrate 16 and the CF substrate 4 are attached by asealing material 6 made of a photo-curing type resin. The photo-curingtype resin of the sealing material 6 to be described in detail later haslight reactive area for the light with the wavelength of a blue-colorband. A liquid crystal 22 is sealed in the area surrounded by thesealing material 6 between the array substrate 16 and the CF substrate4.

Color filters (shown by the letters R(red), G (green), B (blue) in thediagram) along with a common electrode (not shown in the diagram) arearranged on the CF substrate 4. Further, BM's 8 and 18 laminating acolor filter forming material and having a shading function are formedon the CF substrate 4. The BM 18 is used to earn contrast by decidingthe plurality of the pixel areas 14 in the display area 10 and toprevent the light leakage current from generating by shading the TFT 13.Furthermore, a BM picture-frame portion 8 is arranged to shade undesiredlight from outside the display area 10. The BM Picture-frame portion 8,as shown in FIG. 1 b, is formed by laminating (by overlayingcolor-plates) sequentially from the CF substrate 4, for example, ablue-colored layer 24 made of resin dispersing blue-color pigment, agreen-colored layer 26 made of resin dispersing green-color pigment anda red-colored layer 28 made of resin dispersing red-color pigment. FIG.2 shows the photo-transmission spectrum of the red-colored layer 28, thegreen-colored layer 26 and the blue-colored layer 24 when the filmthickness is approximately 1.3 nm and the lateral axis indicates thewavelength and the vertical axis indicates the transmissivity. As shownin FIG. 2, the peak wavelength of the photo-transmission spectrum forthe red-colored layer 28 is equal to 650±10 nm, the peak wavelength ofthe photo-transmission spectrum for the green-colored layer 26 is equalto 540±10 nm and the peak wavelength of the photo-transmission spectrumfor the blue-colored layer 24 is equal to 460±10 nm. By laminating thecolored layers 24, 26 and 28, the three primary colors are overlaid anda shading layer which does not pass the light is formed. The BM 18 isalso formed by overlaying color-plates which is similar to FIG. 1 b.

Further, as shown in FIG. 1 b, an area 20 in which only the blue-coloredlayer 24 is formed to make contact with the sealing material 6 and thegreen-colored layer 26 and the red-colored layer 28 are not formed isarranged in the contacting area of sealing material 6 in the peripheryof the BM picture-frame portion 8.

Thus, this embodiment is the liquid crystal display 1 providing thesealing material 6 made of the photo-curing type material to seal theliquid crystal 22 sandwiched between the two substrates 4 and 16 andshading films 8 and 18 having shading areas overlaying the red-coloredlayer 28, the green-colored layer 26 and the blue-colored layer 24, andhas distinctive characteristics that only the blue-colored layer 24transmitting blue-color light is formed at the shading film 8 areacontacting the sealing material 6 and the photo-curing type material forthe sealing material 6 is, for example, a resin material having thelight reactive area for the light with the wavelength of the blue-colorband. Further, the red-colored layer 28, the green-colored layer 26 andthe blue-colored layer 24 forming the shading areas of the shading films8 and 18 have a distinctive characteristic in using the color filterforming material for each color.

Operational effects by the liquid crystal display according to thisembodiment, having the structure described above and the fabricationmethod of the display are described next. It will be noted that sincethe fabrication method of the liquid crystal display according to thisembodiment has distinctive characteristics in reducing curing defects ofsealing material and steadily performing instillation of liquid crystalin the cell process, other processes such as the array process forming awiring pattern, switching element and the like on the glass substrate,the cell processes of the alignment layer treatment, arrangement of aspacer and the like, or the module processes attaching a driver IC,installing a back lighting and the like are similar to the conventionalmethod and the description is omitted.

FIG. 3 shows the photo-absorption spectrum (β) of the photo-curing typeresin for the sealing material 6 according to this embodiment and theblue-color transmission spectrum (γ) of the blue-colored layer 24 andfurther shows the photo-absorption spectrum (α) of the conventionalphoto-curing type resin for comparison. The lateral axis indicates thewavelength (unit: nm), the vertical axis on the left indicates theextinction rate (unit: none) to compare the photo-absorption spectrum(β) of the photo-curing type resin according to this embodiment and thephoto-absorption spectrum (α) of the conventional photo-curing typeresin. The vertical axis on the right indicates the transmissivity(unit: %) for the blue-color transmission spectrum (γ) of theblue-colored layer 24. As shown in FIG. 3, the peak wavelength of theextinction rate for the photo-curing type resin according to thisembodiment is shifted to the blue-color transmission spectrum (γ) sidein comparison with that of the conventional resin. Further, thehalf-width of the spectrum is wider in comparison with that of theconventional resin and a gentle curve from the peak extends to arelatively wide wavelength band. Accordingly, the photo-absorptionspectrum (β) of the photo-curing type resin according to this embodimentand the blue-color transmission spectrum (γ) of the blue-colored layer24 have an overlapping wavelength band as shown by hatching in FIG. 3.

Thus, even if the sealing material 6 made of the photo-curing type resinaccording to this embodiment contacts with the BM picture-frame portion8 at the area 20, the light in the blue-color band transmitting theblue-colored layer 24 is irradiated in the curing process byirradiation, and thereby the subject area can sufficiently be curedwithout generating curing defects. It will be noted that the reason forusing the blue-colored layer 24 is because the transmission spectrum forblue-color light is most on the short wavelength side as already shownin FIG. 2 and is close to the absorption spectrum for a generalphoto-curing type resin in the transmission spectrum of each color ofthe color filters.

Light reactive area of the photo-curing type resin vary depending on thekind of photo-initiator to be added. In this embodiment, thephoto-initiator having the absorption area on longer wavelength sidethan the past is added to have the wavelength band overlap with thetransmission spectrum of the blue-color resin.

By using this photo-curing type resin, the frame-shape sealing material6 is formed on the array substrate 16 to have the relative positionshown in FIGS. 1 a and 1 b. After performing the instillation of liquidcrystal, the CF substrate is attached to the array substrate 16. At thistime, the blue-colored layer 24 of the BM picture-frame portion 8 and atleast a part of the sealing material 6 overlap in the area 20. Thesealing material curing is performed at this state by irradiating light30 from upper portion of the surface of the CF substrate 4.

By arranging only the blue-colored layer 24 in the area 20 of the BMpicture-frame portion 8 and using the photo curing type resin having thelight reactive area in the transmission wavelength for the blue-colorresin as the forming material of the sealing material 6 in this manner,even if the sealing material 6 contacts with the BM picture-frameportion 8, a light 32 transmitted from the area 20 in the blue-colorwavelength band irradiates the sealing material 6 so that the sealingmaterial 6 is cured. As shown in FIG. 2, since the transmissionwavelength of the blue-color resin is in the range of approximately380-550 nm with the peak in the adjacent of 460 nm, if the photo-curingtype resin having the light reactive area in this range is used as thesealing material 6, curing can be steadily performed even if the sealingmaterial 6 is formed in the BM area 20. Accordingly uncured component ofthe sealing material 6 does not make contact with liquid crystal for along period of time, thereby preventing from liquid crystalcontamination. As a result, while display irregularities due to curingdefects occur all around the edge of seal in the past, a high-qualitypicture without generating display irregularities can be obtained by theliquid crystal display 1 according to this embodiment.

As described above, the fabrication method of the liquid crystal displayaccording to this embodiment seals the liquid crystal 22 by attachingthe two substrates 4 and 16 using the sealing material 6 made of thephoto-curing type material and in the fabrication method of the liquidcrystal display fixing the two substrates 4 and 16 by curing the sealingmaterial 6 by irradiating the light 30, uses the photo-curing type resinhaving the light reactive area to the light with the wavelength of theblue-color band as the photo-curing type material and forms only theblue-colored layer 24 to transmit the light of the blue-color band inthe area 20 of the BM picture-frame portion 8 contacting the sealingmaterial 6 when attaching the two substrates 4 and 16. Further, theblue-colored layer 24 is simultaneously formed when a blue-color colorfilter to be formed in the pixel is formed. Thus, by forming only theblue-colored layer 24 in the area 20, the light 32 in the blue-colorband can be incident upon the sealing material 6 contacting the area 20.Therefore, the sealing material 6 using the photo-curing type resinhaving the light reactive area to the light with the wavelength of theblue-color band can be cured.

Next, a liquid crystal display and a fabrication method thereofaccording to a second embodiment of the present invention is describedwith reference to Table 1 through Table 3 and FIG. 4 a through FIG. 7.It will be noted that the structuring elements having the sameoperational functions as the first embodiment are referred by the samecodes and the descriptions are omitted. FIG. 4 a shows a state of theliquid crystal display according to this embodiment viewed from theopposite substrate 4 side. FIG. 4 b is an enlarged cross sectional viewof a circled area 290 of FIG. 4 a. Although description is omitted inthe first embodiment, as shown in FIGS. 4 a and 4 b, usually a blackmatrix (BM) picture-frame portion 108 for shading is formed in theperiphery of a display area where a color filter (CF) 230 of theopposing substrates is formed. This embodiment has a distinctivecharacteristic in coating the sealing material 6 so that a part of theinternal periphery side of the sealing material 6 formed in the externalperiphery of the display area of the opposite substrate 4 overlaps theBM picture-frame portion 108. Specifically, the sealing material 6 iscoated on the opposite substrate 4 so that the width (A) of the sealingmaterial 6 after pressing is equal to approximately 1.0 mm in width andat the same time the end portion of the sealing material 6 enters towardinside the BM picture-frame portion 108 by a distance of (B)=0.2 mm fromthe end portion of the BM picture-frame portion 108. The sealingmaterial 6 is cured by vertically irradiating UV light from upperportion of the surface of the opposite substrate 4.

The ultraviolet transmissivity of the color plate for the color filter(CF) is described with reference to Table 1. The CF shown in Table 1 isa combination of each CF of the three primary colors red (R), green (G)and blue (B). When a xenon mercury lamp is used as the UV light sourceto cure the sealing material, the peaks of the bright line specificallydegrading liquid crystal by the UV light which transmits and is incidentupon the glass substrate are a line j (313 nm) and a line i (365 nm) asshown in Table 1. The color plate for the color filter hardly transmits(transmissivity 1-2%) the line j and the line i, and the BM does nottransmit either the line j nor the line i as well.

TABLE 1 Table 1 A table showing the transmissivity of ultravioletthrough color plate for color filter Peak of Bright Line 250 nm 313 nm(j) 365 nm (i) Glass 35% 79%  86% CF 0% 0% 1.5%

Next, a comparison of electric characteristics of liquid crystal whenultraviolet is irradiated with and without the color filter is shown inTable 2. In Table 2, the code “->” indicates variation before and afterthe UV irradiation. It will be noted that the irradiating direction ofthe UV light is the direction vertical to the substrate surface. Whenthe ultraviolet is irradiated from upper part of an evaluation cell,while the degradation of the electric characteristics of liquid crystal“without CF (color filter)” is prominent, “with CF” has little effects.

TABLE 2 Table 2 A table showing the electric characteristics of liquidcrystal with and without CF Voltage retention Ion Density ratio (pc/cm²)(%) Without CF 20 -> 463 98.9 -> 88.2 With CF 18 -> 35  98.9 -> 98.9

Therefore, if the color filter is used as a shading mask against the UVlight, damages to the liquid crystal can be suppressed and other shadingmask for each pattern to form the sealing material 6 is not required toprepare. Further, since the end portion of the sealing material 6overlaps in the BM picture-frame portion 108, the liquid crystal 22 doesnot expose between the end portion of the sealing material 6 and the endportion of the BM picture-frame portion 108 and thereby the liquidcrystal is not directly irradiated by the ultraviolet and thedegradation of the liquid crystal can be prevented. Accordingly, ahigh-quality picture display without display irregularities can beperformed. Furthermore, enlarging an outside dimension of a panel atinstillation can be suppressed.

On the other hand, the conventional liquid crystal display is shown inFIGS. 5 a and 5 b as a comparative example. FIG. 5 a shows a state ofthe conventional liquid crystal display viewed from an oppositesubstrate 200 side. FIG. 5 b is an enlarged cross sectional view of acircled area 292 of FIG. 5 a. In this comparative example, a space 220is formed between the internal periphery side of a sealing material 202formed in the external periphery of the display area of the oppositesubstrate 200 and the BM picture-frame portion 108 and the liquidcrystal inside is in a state to be seen through the glass substrate.Specifically, the sealing material 202 is coated on the oppositesubstrate 200 so that the width (C) of the sealing material 202 afterpressing is equal to approximately 1.0 mm and the distance (D) betweenthe end portion of the sealing material 202 and the end portion of theBM picture-frame portion 108 is equal to 0.5 mm. The sealing material202 is cured by irradiating the UV light vertically from upper part ofthe substrate surface of the opposite substrate 200. As a result, sincethe liquid crystal layer exposes when irradiating the UV in thiscomparative example, display irregularities due to degradation of liquidcrystal occur all around the edge of seal. Further, the distance (D)between the end portion of the sealing material 202 and the end portionof the BM picture-frame portion 108 becomes an obstacle to reduce theoutside dimension of the panel.

Although in the above embodiment, the distance (B) overlapping thesealing material 6 and the BM picture-frame portion 108 is equal to 0.2mm, the overlapping distance can be lengthened to approximately (B)=0.5mm. Usually, when overlapping of the sealing material 6 and the BMpicture-frame portion 108 is large, the end portion of the sealingmaterial 6 is non-photo-curable. Since when the light initiator isirradiated and cloven activated species spread, the sealing material 6can be cured if an overlapping distance is moderately fair even if thereis a shading portion. Further, if a metal film exists on the lowersurface of the sealing material 6, the light transmitted through thephoto-curing resin performs a multiple reflections on the metal film,thereby effectively utilizing the energy from the UV light. This issimilar to the first embodiment. Furthermore, if the UV light candirectly reach the sealing material 6 in the area where UV light isincident diagonally and overlapped, the overlapping distance (B) can beequal to approximately 0.5 mm.

A comparison between the seal shading distance and the curability isshown in Table 3. This is the result when an acrylic type resin is usedfor a photo-curing resin, a cell is made by instillation and a part ofthe sealing material 6 is shaded, and then the UV light is irradiatedfrom the vertical direction to and from the diagonal direction of 45° inangle from the surface of the opposite substrate 4. The comparison ofcurability is performed by observing the alignment of the edge of theseal and measuring the electric characteristics of the liquid crystalafter annealing. According to the result of measuring, the shadingdistance (B) possible for curing when irradiated only from the verticaldirection is equal to approximately 0.2 mm. As described in the firstembodiment, if a light reflection layer (metal film) is on the arraysubstrate 16, the UV light having transmitted through the sealingmaterial 6 is reflected on the light reflection layer and again used forcuring the sealing material 6 so that the shading distance (B) possiblefor curing is equal to approximately 0.3 mm. Further, when the lightreflection layer is on the array substrate 16 and at the same time theUV light is incident from diagonal 45° angle, the shading distance (B)possible for curing is equal to approximately 0.5 mm. In table 3, whenalignment irregularities occur or the reduction of the voltage retentionratio is more than 1%, photo-curing is considered unsatisfactory andindicated by X and satisfactory photo-curing is indicated by O.

TABLE 3 Table 3 A table showing the relation between the seal shadingdistance and curability Shading Irradiation Distance Under the SealDirection Curability 0.0 mm Glass Vertical ◯ 0.2 mm Glass Vertical ◯ 0.3mm Glass Vertical X 0.3 mm Metal Film Vertical ◯ 0.5 mm Metal FilmVertical X 0.5 mm Metal Film Diagonal 45° ◯

Next, an improved structure related to the overlapping distance (B) ofthe sealing material 6 and the BM picture-frame portion 108 is describedwith reference to FIG. 6. FIG. 6 shows a state of the upper left portionof the panel viewed from the opposite substrate 4 side. As shown in FIG.6, the sealing material 6 is usually formed curving in an arc shape atcorner portions of the panel. Thus, in this example, corner portions ofthe BM picture-frame portion 108 are also curved into the arc shapealong the curves of the sealing material 6. Specifically, the sealingmaterial 6 having a width of 1 mm is curved into the arc shape at cornerportions of the panel and accordingly the end portions of the BMpicture-frame portion 108 overlapping with the sealing material 6 by 0.5mm in width is also formed curving into the arc shape with a radius of 1mm.

FIG. 7 is shown as a comparative example to the aforementioned. Thecorner portion of the BM picture-frame portion 108 shown in FIG. 7 isbent at a right angle unrelated to the arc-shape curve of the sealingmaterial. Therefore, as shown in the diagram, an area where the overlapbetween the sealing material 6 and the BM picture-frame portion becomes0.9 mm is generated. Since the sealing material 6 in such an area is notcured by the irradiation of UV light as evident in Table 3, thepossibility of generating display irregularities in four corners of thedisplay area exists.

By keeping the width overlapping the corner portions of the BMpicture-frame portion 108 and the sealing material 6 within apredetermined range in the manner shown in FIG. 6 and by making the areaoverlapping the sealing material 6 and the BM picture-frame portion 108substantially the same all around the panel, the sealing material 6 allaround the panel can be sufficiently cured and a high-quality picturewithout display irregularities can be displayed.

Next, a liquid crystal display and a fabrication method thereofaccording to a third embodiment of the present invention is describedwith reference to FIG. 8 a through FIG. 9. It will be noted thatstructuring elements having the same operation functions as the firstand the second embodiments are referred by the same codes, and thedescriptions are omitted. FIGS. 8 a and 8 b show a transfer 233according to this embodiment arranged in the BM picture-frame portion108. FIG. 9 shows a vicinity of the BM picture-frame portion 108provided with the similar transfer to the past for comparison. Theconventional transfer 231 shown in FIG. 9 is formed in the BMpicture-frame portion 108 adjacent to the sealing material 6. Thetransfer 233 according to this embodiment is also formed in the BMpicture-frame portion 108 adjacent to the sealing material 6 in thesimilar manner to the past. Each of the transfers 231 and 233 areelectrically connected to both of the substrates via transfer pads 232and 234.

A plurality of long and narrow rectangular-shape slits 236 are opened inthe BM area on the transfer pad 234 shown in FIG. 8 a. The length (H) ofa long side of the slit 236 is equal to approximately 1.00 mm and thelength (I) of a short side is equal to approximately 0.2 mm. The length(J) of the space between the adjacent slits 236 is equal to 0.2-0.8 mm.A black-color conductive spacer depositing nickel (Ni) is added to thetransfer 233. Slits are not formed on the conventional transfer 231shown in FIG. 9 and the transfer 231 is shaded by the BM film.

A method of UV irradiation is similar to the above embodiments alreadydescribed. As a result of UV irradiation, display irregularities occurdue to curing defects of the transfer 231 in the conventional example.In this embodiment, display irregularities also occur due tophoto-curing defects of the transfer 233, although better than theconventional example, when the length (J) of the space between theadjacent slits 236 is more than 0.6 mm. When the length (J) of the spacebetween the slits 236 is less than 0.4 mm, neither displayirregularities nor light leakage from back lighting occur.

Although it is possible to form the transfer 233 outside the sealingmaterial 6, the outside dimension of the panel enlarges. Thus, thetransfer 233 is required to be formed inside the sealing material 6 in anarrow picture-frame panel. In this case, the transfer 233 is formed inthe BM picture-frame portion 108 and photo-curing defects are mostlikely to occur. Then, as the liquid crystal display according to thisembodiment, light transmission windows such as the slit 236 and the likeare arranged in the transfer area of the BM picture-frame portion 108and colored particles such as the aforementioned black-color conductivespacer and the like are added to the transfer 233. Thus, photo-curingdefects of the transfer 233 are eliminated and light leakage from thelight transmission windows can be suppressed by mixing black-color ordark-color conductive particles in the transfer 233.

Further, as described above, a shape of the light transmission window isdesired to be substantially the rectangular-shape slit and the slits aredesired to be arranged so that the length (J) of the space between theadjacent slits are less than 0.4 mm. Furthermore, when colored-particlesin the transfer 233 alone are insufficient to shade the lighttransmission windows, the light transmission windows are not required tobe for a whole surface transmission and photo-curing is possible even ifthe window is substantially the rectangular-shape slit as long as thespace between the slits is within the spreading distance of activatedspecies. Since the spreading distance of the photo-cloven activatedspecies is usually approximately 0.2 mm, the length (J) of the spacebetween the slits is desired to be less than 0.4 mm even whenconsidering to spread from both adjacent slits. It will be noted thatsince the colored particles are mixed in the transfer 233 in thisembodiment, little UV light transmits the transfer 233 and curing by thewraparound of light due to multiple reflection described above canhardly be expected.

Further, the shape of the light transmission window may be substantiallythe circular-shape dot and the dots may be arranged so that the length(J) of the space between the dots is less than 0.4 mm. In the similarmanner described above, even when the light transmission windows arecircular-shape dots, as long as the length of the space between theadjacent dots is within the spreading distance of the activated species,photo-curing is possible and substantially the same exterior view as theother BM picture-frame area can be obtained.

Next, a liquid crystal display and a fabrication method thereofaccording to a fourth embodiment of the present invention is describedwith reference to FIGS. 10 a, 10 b and FIG. 11. It will be noted thatstructuring element having the same operational functions as the firstthrough the third embodiments are referred by the same codes and thedescriptions are omitted. This embodiment has a distinctivecharacteristic in a UV light source irradiating UV light to the sealingmaterial 6 and a line (linear) light source in accordance with the shapeof the sealing material 6 is used. In order to photo-cure thephoto-curing resin, the light more than the curing illuminance isrequired for irradiation. In case of photo-curing resin by ultravioletlight, the irradiation illuminance equal to approximately 50-100 mW/cm²is required. In order to obtain this illuminance by surface irradiationby the conventional light source, the lamp output is required to be madelarge and it is not practical. In the structure according to thisembodiment, since only the predetermined area of the sealing material isirradiated, the lamp output can be suppressed and furthermore, since thewhole irradiation is possible, occurrences of misalignment of thesubstrates are also reduced.

FIG. 10 a is an oblique view showing the UV light source and a state ofusing the UV light source according to this embodiment. FIG. 10 b showsa part of the cross section cut at a line A-A of FIG. 10 a.

A UV light source 64 shown in FIGS. 10 a and 10 b are arranged in upperpart of an attached substrate 62 of the array substrate 16 and theopposite substrate 4 with a predetermined distance and has a line lightsource 66 in a similar shape to the frame shape of the sealing material6 and arranged outside the sealing material 6 slightly larger than theframe of the sealing material 6 on a flat surface substantially parallelto the surface of the attached substrate 62.

As shown in FIG. 10 b, the upper surface of the sealing material 6enters inside the BM picture-frame portion 108 by the width X. The UVlight emitting from the line light source 66 enters inside the sealingmaterial 6 from the area not overlapping with the BM picture-frameportion 108 on the surface of the sealing material 6. The incident angleθ at this time is approximately 45°. In such a structure, the lamp lightsource 64 can be arranged closely to the sealing material 6. Therefore,the same intensity of radiation as in the past can be irradiated by thelamp output as low as several hundred W. Further, since only a part ofthe attached substrate 62 is irradiated, an increase in temperature ofthe attached substrate 62 by irradiation can be suppressed and themisalignment between the array substrate 16 and the opposite substrate 4due to thermal expansion can also be suppressed within 3 μm.

Thus, according to the UV irradiation light source 64 in thisembodiment, the UV light can wraparound as far as the lower part of theBM picture-frame portion 108 since the light is irradiated from theoutside diagonal direction (for example, diagonally 45°) of the BMpicture-frame portion 108 with respect to the coating surface of thesealing material 6. Therefore, the overlap X between the sealingmaterial 6 and the BM picture-frame portion 108 can be enlarged toapproximately 0.8 mm, thereby further reducing the outside dimension ofthe panel. When the metal film exists on the lower surface of thesealing material 6, since the multiple reflection of the UV light by thediagonal irradiation is obtained, the overlap X between the sealingmaterial 6 and the BM picture-frame portion 108 can be further expandedand the outside dimension of the panel can be further reduced. It willbe noted that although the amount of light wraparounding the lower partof the BM picture-frame portion 108 by diagonal the lower part of the BMpicture-frame portion 108 by diagonal irradiation increases, theintensity of irradiation to the coating surface of the sealing material6 becomes lower than the irradiation from the vertical direction. Amountof light wraparounding due to the diagonal irradiation and intensity ofirradiation on the coating surface of the sealing material are in atrade-off relationship and the irradiation from the angle ofsubstantially 45° can be most effective.

A conventional UV irradiation light source 70 is shown in FIG. 11 forcomparison. In order to obtain the ultraviolet illuminance equal to 100mw/cm², the surface irradiation by the conventional light source shownin FIG. 11 requires the high lamp output as large as several kW. Theattached substrate 62 is heated to a high temperature by beingirradiated on the whole surface, thereby resulting in a misalignment byapproximately 7-10 μm.

The liquid crystal display according to a fifth embodiment of thepresent invention is described with reference to FIG. 12 a through FIG.16. First, the schematic structure of the liquid crystal displayaccording to this embodiment is described with reference to FIGS. 12 aand 12 b. FIG. 12 a shows a part of the upper surface of an activematrix-type liquid crystal display panel 1 using the TFT as a switchingelement viewed from the CF substrate side. FIG. 12 b shows a partialcross section cut at a line A-A of FIG. 12 a. A plurality of pixel areas14 arranged in a matrix shape are formed on the array substrate 16 sideof the liquid crystal display panel 1, and a TFT (not shown in thediagram) is formed in each of the pixel area 14. The picture displayarea 10 is structured by the plurality of the pixel areas 14. Although adetailed diagram is omitted, the gate electrode of the TFT in each pixelarea 14 is connected to a gate wiring and a drain electrode is connectedto a data wiring respectively. Further, the source electrode of the TFTis connected to a pixel electrode formed in the pixel area 14. Aplurality of data wirings and gate wirings are connected to a terminalportion 2 formed in the external periphery of the array substrate 16,thereby a plurality of data wirings and gate wirings are to be connectedto a driving circuit (not shown in the diagram) provided externally.

The CF substrate 4 is formed slightly smaller than the array substrate16 by substantially the width of the terminal portion 2 and is arrangedfacing the array substrate 16 sealing the liquid crystal 22 at apredetermined cell gap. The array substrate 16 and the CF substrate 4are attached by a main seal 6 made of photo-curing type resin. The width6′ indicated by the two dotted lines in the diagram shows the width whenthe main seal 6 is coated. A frame-shape structure 12 separating themain seal 6 from the liquid crystal 22 is formed in an area between themain seal 6 and the display area 10. The liquid crystal 22 is sealed inan area surrounded by the frame-shape structure 12 between the arraysubstrate 16 and the CF substrate 4.

Color filters (indicated by the letters R(red), G(green), B(blue) in thediagram) as well as a common electrode (not shown in the diagram) areprovided on the CF substrate 4. Further, a BM picture-frame 8 and a BM18 having a shading function are formed on the CF substrate 4. The BMpicture-frame 18 is provided to shade undesired light from outside thedisplay area 10. The BM 18 is used to earn contrast by deciding theplurality of the pixel areas 14 in the display area 10 and to preventlight leakage current from generating by shading the TFT.

The peripheral end of the frame-shape structure 12 is arranged to besubstantially in accordance with the peripheral end of the BMpicture-frame 8 viewed from the vertical direction to the surface of thearray substrate 16. Therefore, even if the internal peripheral endportion of the main seal 6 is formed adjacent to the external peripheralend portion of the BM picture-frame 8, the internal peripheral endportion of the main seal 6 does not overlap the external peripheral endportion of the BM picture-frame 8 as long as the main seal 6 does notflow beyond the frame-shape structure 12 after attaching. Accordingly,since the shading of the UV light by the BM picture-frame 8 does notoccur, a curing defect of the main seal 6 does not occur. It will benoted that depending on the curing characteristics of the main seal 6,since there is a case in which curing is possible by spreading thereaction activated species even if there is a certain shaded area, thegeneration of the shaded area as wide as approximately the spreadingdistance of the reaction activated species in the BM picture-frame 8 isnot a problem. For example, when the width of the main seal 6 is equalto 1-2 μm after attaching the substrates, depending on the BMpicture-frame 8, shading the width equal to approximately 200 μm is nota problem.

Thus, the liquid crystal display according to this embodiment has themain seal 6 attaching the substrates 16 and 4 in the external peripheralportion of the display area 10 of the two opposite substrates 16 and 4sandwiching the liquid crystal 22 and frame-shape structure 12 and theBM picture-frame 8 formed in the area between the main seal 6 and thedisplay area 10. The frame-shape structure 12 and the BM picture-frame 8are formed so that the external peripheral end of the frame-shapestructure 12 is substantially in accordance with the external peripheralend of the BM picture-frame 8 viewed from the vertical direction to thesurface of the substrate 16. According to this structure, when thecoated main seal 6′ spreads and becomes the main seal 6 after attachingthe substrates 16 and 4, the possibility that a part of the main seal 6enters the external peripheral portion of the BM picture-frame 8 iseliminated. Accordingly, a phenomenon of UV light not to reach a part ofthe main seal 6 and to generate curing defects is prevented and the mainseal which does not easily peel off can be obtained. Further, since thecoating position of the main seal can be adjacent to the externalperiphery end portion of the BM picture-frame 8, enlargement of thepicture-frame area can be suppressed, thereby effectively utilizing thesurface of the glass substrate.

Next, the structure of an example of a variation of the liquid crystaldisplay according to this embodiment is described with reference toFIGS. 13 a and 13 b. FIGS. 13 a and 13 b show partial cross sections cutat the line A-A of FIG. 12 a. FIG. 13 a shows a state in which avertical alignment film 14 is formed in the display area 10 of the arraysubstrate 16 and on the surface opposing to the frame-shape structure12. Further, FIG. 13 b shows a state in which a vertical alignment film13 is formed on the surface of the end portion of the frame-shapestructure 12. Pillar-shape spacers 15 to obtain a predetermined cell gapare formed in both FIGS. 13 a and 13 b.

Furthermore, the frame-shape structure 12 has a height which is morethan substantially half the height of the spacer 15 in both FIGS. 13 aand 13 b. As described above, when the frame-shape structure 12 with asimilar thickness of the cell gap is only provided in the fringeperiphery, liquid crystal flows over the frame-shape structure 12 atinstillation. However, if the vertical alignment film 13 is formed onthe surface of the frame-shape structure 12 and the vertical alignmentfilm 14 exists on the surface opposing to the frame-shape structure 12,the wettability of the liquid crystal 22 is reduced due to the verticalalignment films 13 and 14, therefore the liquid crystal 22 can not flowover the space between the frame-shape structure 12 and the arraysubstrate 16 to reach the main seal 6 while the main seal 6 is undercuring. It will be noted that although the liquid crystal 22 reaches themain seal 6 if time is taken, if the height of the frame-shape structure12 is higher than half of the height of the spacer 15 in the displayarea 10 (for example, approximately 2 μm when the cell gap is 4 μm),several tens of minutes are required for the liquid crystal 22 to flowover the frame-shape structure 12 and reach the main seal 6. If the mainseal 6 is cured during that time period, the liquid crystal 22 is notcontaminated.

Further, the main seal 6 is required to be formed in a position wherethe internal peripheral end portion of the main seal 6 does not flowover the external peripheral end portion of the frame-shape structure 12after the gap is created. Furthermore, the main seal 6 is desired to beformed in a position where the internal peripheral end portion of themain seal 6 is adjacent to the external peripheral end portion of theframe-shape structure 12 after the gap is created. If the main seal 6 iscoated too closely to the frame-shape structure 12, the internalperipheral end portion of the main seal 6 flows over the externalperipheral end portion of the frame-shape structure 12 in the processcreating the gap, thereby resulting in curing defects of the sealingmaterial and irregular cell gaps. On the other hand, if there is spacebetween the main seal 6 and the frame-shape structure 12, thepicture-frame area of the panel is enlarged and a possibility of notbeing able to effectively utilize the surface of the glass substrate isgenerated and when the liquid crystal panel is expanded or contracteddue to extreme variations in temperature, a possibility that vacuum airbubbles in the space enter in the display area 10 increases.

Next, the structure of an example of other variation of the liquidcrystal display according to this embodiment is described with referenceto FIGS. 14 a and 14 b. FIG. 14 a shows a part of the upper surface ofthe active matrix-type liquid crystal panel 1 using the TFT as aswitching element viewed from the CF-substrate side. FIG. 14 b showspartial cross section cut at a line A-A of FIG. 14 a. The samestructuring elements as in the liquid crystal display shown in FIG. 12 athrough FIG. 13 b are referred by the same codes and the descriptionsare omitted.

In the liquid crystal display shown in FIGS. 14 a and 14 b, theframe-shape structure 12 separating the main seal 6 from the liquidcrystal 22 is formed in the area inside the main seal 6 and outside thedisplay area 10 and a second frame-shape structure 12′ separating themain seal 6 from the external peripheral portion of the main seal 6 isformed in the area to be outside the main seal 6, therefore both sidesof the main seal 6 is surrounded by the frame-shape structures 12 and12′. The frame-shape structure 12′ is provided to easily pressurize themain seal 6. By pressurizing from both sides of the main seal 6, the gapfor the main seal 6 is easily created.

The frame-shape structures 12 and 12′ have the height more than half theheight of the spacer 15 in the display area 10, and the verticalalignment films 13 or 14 (the vertical alignment film 13 is shown inFIGS. 14 a and 14 b) is formed on the surface of or in the area opposingto the frame-shape structure 12. This vertical alignment film 13 or 14is formed for the similar reason to the example of the variationdescribed with reference to FIGS. 13 a and 13 b. Further, in order toprevent the peeling of the seal from generating by the reduction of theadhesive strength of the main seal 6, the vertical alignment film 14 isdesired to be formed beyond the frame-shape structure 12 not to overlapthe main seal 6.

Furthermore, the distance of the space between the frame-shapestructures 12 and 12′ is more than the width, preferably substantiallythe same width, of the main seal 6 after the gap is created, and themain seal 6 is arranged in a position where the internal and theexternal peripheral end portions of the main seal 6 do not flow over theexternal peripheral end portion of the frame-shape structure 12 and theinternal peripheral end portion of the frame-shape structure 12′, afterthe gap is created, preferably in a position adjacent to the frame-shapestructures 12 and 12′.

Also this example of the variation has a distinctive characteristic informing a part or all of the frame-shape structures 12 and 12′ in the BMpicture-frame 8 and not forming the BM in the space portion between theframe-shape structures 12 and 12′. If the frame-shape structures 12 and12′ are arranged in the BM picture-frame 8, and the space portionbetween the frame-shape structures 12 and 12′, in other words, the areathe main seal 6 is coated is opened so that UV irradiation can beperformed, the main seal 6 can be completely cured and at the same timethe area required to form the main seal 6 outside the BM picture-frame 8in the past is no longer required.

Further, the frame-shape structure 12 is desired to be formed using aresin material which does not substantially transmit the wavelength ofUV. At instillation, UV irradiation is performed from the CF substrateside which does not have the metal film in the main seal area so thatthe UV light is not shaded. Usually, although a mask is covered on thedisplay area 10, a part of the UV light is reflected on the metal filmformed on the array substrate 16 and enters the display area 10 side.This is a phenomenon called the light incidence or light wraparound bythe multiple reflection. Photolysis of the liquid crystal 22 occurs dueto this light, thereby resulting in the generation of display defects onthe edge of the seal. Therefore, if a resin material which does notsubstantially transmit the wavelength of UV is used as the frame-shapestructure 12, the multiple reflection component is absorbed by theframe-shape structure 12, the liquid crystal 22 at the edge of the sealis not irradiated by UV, thereby preventing the liquid crystal 22 fromdegrading.

The structure described above is most effective when an instillingmethod is used in the fabrication of the liquid crystal display.Prominent effects such as preventing the main seal 6 from curing defectsdue to shading, further preventing the uncured main seal 6 fromcontacting the liquid crystal 22, and preventing the liquid crystal 22from being irradiated by the UV light when photo-curing the main seal 6can be obtained by the instilling method, thereby greatly improving thereliability of instillation.

Further, when instillation is used, as shown in FIG. 16, after attachingthe substrates 16 and 4 and before a liquid crystal boundary 23 of theliquid crystal 22 reaches the frame-shape structure 12, the gap adjacentto the frame-shape structure 12 is created by pressurizing theframe-shape structure 12 by a pressure P, thereby preventing the liquidcrystal 22 from entering onto the frame-shape structure 12 and largelyreducing the time required to create the gap of the main seal 6 as well.

Next, the fabrication method of the liquid crystal display according tothis embodiment is described by using examples.

Example 1

A colored-resin film (red/made by JSR (Japan Synthetic Rubber))dispersed by pigment is evenly coated on the CF substrate and the spacer15 of the display area 10 and the frame-shape structure 12 are patternedby photolithography process. The height of the spacer 15 of the displayarea 10 is equal to 4.0 μm in height and three kinds of the frame-shapestructures 12 are formed into 4.0 μm (Example A), 3.0 μm (Example B) and2.0 μm (Example C) in height. Further, the spacer 15 is formed in anon-pixel area of the display area 10 and the frame-shape structure 12is formed in the area inside the main seal 6 and at the same timeoutside the display area so that the external peripheral end portion ofthe BM picture-frame 8 is substantially in accordance with the externalperipheral end portion of the frame-shape structure 12 viewed from thedirection vertical to the surface of the array substrate 16.

Further, comparative example A is structured by entering the externalperipheral end portion of the frame-shape structure 12 to inside of theexternal peripheral end portion of the BM picture-frame 8 by 0.5 mm. Thevertical alignment film (made by JSR) 14 is formed on the CF substrate 4and the array substrate 16. The vertical alignment film 14 is formed tobe substantially in accordance with the external periphery portion ofthe frame-shape structure 12 viewed from the direction vertical to thesurface of the array substrate 16.

Furthermore, comparative example B is structured without forming avertical alignment film on the surface of the frame-shape structure 12and the area opposing the frame-shape structure 12.

The main seal (made by Kyoritsu Kagaku) 6 is coated so that the internalperiphery of the main seal 6 is adjacent to the external periphery ofthe frame-shape structure 12 after the gap is created. Since the widthof the main seal is equal to 1 mm after the gap is created in thisembodiment, a seal line is 0.5 mm-apart from the external periphery ofthe frame-shape structure 12. In comparative example C, the seal line is2.0 mm apart from the frame-shape structure 12.

The required volume amount of the liquid crystal 22 obtained from theinternal periphery of the frame-shape structure 12 and the height of apattern is dropped on the display area 10 and the substrates 16 and 4are attached in a vacuum. After attachment, atmospheric pressure isrestored, the liquid crystal is spread and the gap is created. After thegap is created, the spread of the liquid crystal 22 substantially intothe display area 10 is confirmed. Then, the main seal is cured byperforming UV irradiation from upper part of the CF substrate 4. Theattached substrates are scribed and broken and the liquid crystal panelis completed. After the liquid crystal panel is heated (isotropictreatment) at 100° C. for one hour, a lighting inspection and a sealpeeling test are performed.

Results of the tests are shown in Table 4. In Comparative Example A, anoverlap (shaded area) with the BM picture-frame 8 is created by thecircular arc portion of the corner portion of the seal and displayirregularities and peeling of the seal due to curing defects occur. InComparative Example B, a part of the liquid crystal 22 flows over theframe-shape structure 12 and contacts with the uncured main seal 6 afterattachment and display irregularities occur from the peripheral portionof the frame-shape structure 12. In Comparative Example C, althoughdisplay irregularities do not occur, vacuum air bubbles are generated atcorner portions after the heating. On the other hand, in Example A, Band C, none of the irregularities occur.

TABLE 4 Table 4 Results of the panel tests of Comparative Examples A, Band C and Examples A, B and C Lighting Remarks Test Peeling TestComparison Corner portions Display Peeling at Example A shadedirregularities less than 1.5 Others same as at corner kgf/mm Example Aportions and peripheral portion Comparison No vertical Display Nopeeling at Example B alignment film irregularities 1.5 kgf/mm Otherssame as at peripheral Example A portion Comparison Space in the sealVacuum air No peeling at Example C Others same as bubbles at 1.5 kgf/mmExample A corner portions Example A Improved Excellent No peeling atComparative 1.5 kgf/mm Examples A, B & C Height of structure 4 μmExample B Improved Excellent No peeling at Comparative 1.5 kgf/mmExamples A, B & C Height of structure 3 μm Example C Improved ExcellentNo peeling at Comparative 1.5 kgf/mm Examples A, B & C Height ofstructure 2 μm

Example 2

A colored-resin film (red/made by JSR) dispersing pigment is evenlycoated on the CP substrate 4 and the spacer 15 of the display area 10,and the frame-shape structures 12 and 12′ are patterned byphotolithography process. The height of the spacer 15 of the displayarea 10 is equal to 4.0 μm, three kinds of the frame-shape structures 12and 12′ are formed into 4 μm (Example D), 3.0 μm (Example E), and 2.0 μm(Example F) in heights, the size of the pattern for the spacer 15 isequal to 10 μm□, the width of the frame-shape structures 12 and 12′ isequal to 0.75 mm, and the frame-shape structures 12 and 12′ are similarfigures to the main seal 6. The position of the pattern for the spacer15 is in the non-pixel area of the display area 10, the frame-shapestructure 12 is in the area inside the main seal 6 and at the same timeoutside the display area 10 and the frame-shape structure 12′ is apart 1mm from the frame-shape structure 12. In this example, the width of theBM picture-frame 8 is equal to 2.5 mm so that the whole frame-shapestructures 12 and 12′ can be contained in the above area. Accordingly,the main seal area which is outside the BM picture-frame in the past canbe eliminated, thereby realizing narrowing of the picture-frame by 1 mmon each side or 2 mm in panel measurement.

Then, the vertical alignment film (made by JSR) 14 is formed on the CFsubstrate 4 and the array substrate 16 so as to be level with theexternal periphery of the frame-shape structure 12. Further, asComparative Example D, a structure forming the vertical alignment film14 in the external periphery and the opposite area of the frame-shapestructure 12 is structured. The main seal (made by Kyoritsu Kagaku) 6 iscoated so that the internal and external peripheries of the main seal 6are adjacent to the internal and external peripheries of the frame-shapestructures 12 and 12′. The following is the liquid crystal panelcompleted by the similar method to the Example 1 and provided to thepanel test.

Results of the tests are shown in Table 5. In Comparative Example D,since the vertical alignment film 14 is formed under the main seal 6,adhesive strength is weaker than the glass surface and peeling of theseal occurs. On the other hand, peeling of the seal did not occur inExamples D, E and F.

TABLE 5 Table 5 Results of the panel tests of Comparative Example D andExample D, E and F Remarks Lighting Test Peeling Test ComparativeAlignment film under Excellent Peeling at Example D the seal less than1.5 Others same as kgf/mm Example D Example D Improved ComparativeExcellent No peeling at Example D 1.5 kgf/mm Height of structure 4 μmExample E Improved Comparative Excellent No peeling at Example D 1.5kgf/mm Height of structure 3 μm Example F Improved Comparative ExcellentNo peeling at Example D 1.5 kgf/mm Height of structure 2 μm

Example 3

A colored-resin film (red/made by JSR) dispersing pigment is evenlycoated on the CF substrate 4 and the spacer 15 of the display area 10and the frame-shape structure 12 are patterned by photolithographyprocess. Further, as a Comparative Example E, the similar pattern isstructured by transparent resin (made by JSR). The height of the patternis equal to 4.0 μm for both and the following is the liquid crystalpanel completed by the similar method to Example 1 and provided to thepanel test.

The UV spectrums for Comparative Example E and Example G are shown inFIG. 15. In FIG. 15, the lateral axis indicates wavelength and thevertical axis indicates transmissivity. Although light in thelong-wavelength side of more than 300 μm among the UV wavelengths istransmitted in Comparative Example E (a curved line (β) in FIG. 15), itis known that the colored resin in Example G (a curved line (α) in FIG.15) hardly transmits light. The results of the panel tests are shown inTable 6. In comparative Example E, since the light component of multiplereflection generated by UV irradiation when curing the seal enters intothe display area 10 via the transparent resin, photolysis of the liquidcrystal 22 occurs, thereby resulting in the generation of displayirregularities all around the periphery. On the other hand, displayirregularities do not occur in Example G.

TABLE 6 Table 6 Results of the panel tests of Comparative Example E andExample G Remarks Lighting Test Peeling Test Comparative Above structurewith Display No peeling at Example E transparent resin irregularities1.5 kgf/mm Others same as all around the Example G edge Example GImproved Comparative Excellent No peeling at Example E 1.5 kgf/mm

A colored-resin film (red/made by JSR) dispersing pigment is evenlycoated on the CF substrate 4 and the spacer 15 of the display area 10and the frame-shape structure 12 are patterned by photolithographyprocess. The height of the pattern is equal to 4.0 μm for both and thefollowing is the attachment performed in a vacuum by the similar methodto Example 1. After being released in an atmosphere, the gap of theframe-shape structure 12 is created by pressurizing the frame-shapestructure 12 portion at 1.0 kgf/cm² before the liquid crystal 22 and themain seal 6 reach the frame-shape structure 12. Further, ComparativeExample F releasing the air without performing partial pressurization isstructured. After the gap is created, the time substantially spreadingthe liquid crystal 22 in the display area 10 is measured and thefollowing is the liquid crystal display panel is completed by thesimilar method to Example 1. After heating at 100° C. for one hour(isotropic treatment), the cell gap adjacent to the seal is measured.

Results are shown in Table 7. Although the picture area equivalent to 15inches in size is used as the liquid crystal display panel,approximately 10 minutes is required in Example F to substantiallyspread the liquid crystal 22 in the display area 10. Further, althoughthe cell gap inside the picture area is equal to 4.0-4.1 μm, the cellgap adjacent to the seal is greater by +0.1-0.2 μm. If the amount ofliquid crystal to be dropped is further reduced, this difference can bereduced. However, several tens of minutes are required to substantiallyspread the liquid crystal in the picture area, therefore reducing theamount of liquid crystal to be dropped is not practical. On the otherhand, the time spreading the liquid crystal is shortened toapproximately 3 minutes in Example H and the cell gap adjacent to theseal is approximately the same as the cell gap inside the picture area.

TABLE 7 Table 7 Comparison of Comparative Example F and Example H Timespreading Liquid Remarks Crystal Cell Gap Comparative Gap created solely~10 min. 4.2~4.3 μm Example F by releasing in an atmosphere Example HAfter releasing in  ~3 min. 4.0~4.1 μm an atmosphere, the frame-shapestructure partially pressurized

Thus, the liquid crystal panel can be fabricated with favorable yieldaccording to this embodiment even if a vacuum injection method or aninstilling method is used and the cost of liquid crystal display panelcan be further reduced, thereby expanding the scale of the market as thedisplay substituting CRT.

Next, a liquid crystal display and a fabrication method thereofaccording to a sixth embodiment of the present invention are describedwith FIG. 17 through FIG. 24. The black matrix (BM) is formed at aperipheral edge portion of the liquid crystal display panel and if thereis no margin at a position the seal is coated, a part of the sealoverlaps with the end of the BM picture-frame after attachment. Ifultraviolet light is irradiated from the direction vertical to thesubstrate, the ultraviolet light is shaded in the portion overlappingwith the BM picture-frame and the seal can not be cured. The adhesivestrength of the seal is reduced in this portion and peeling of the sealoccurs. Further, since the seal remains uncured, when the liquid crystalpanel expands or contracts due to variations of temperature, the sealcomponent is eluted and the voltage retention ratio at the edge of theseal is reduced. If the seal coating position is sufficiently apart fromthe end of the BM picture-frame, such defects do not occur. However,coating the seal sufficiently apart from the end of the BM picture-frameinduces the picture-frame area to be enlarged and is not appropriate.

In this embodiment, the above problems are solved by using the followingmethods:

(1) By using ultraviolet-light-curing resin for the main seal, theframe-shape structure hardly transmitting ultraviolet light is formedinto a height equivalent to the thickness of the panel in the areainside the main seal and at the same time outside the display area. Theseal-curing is performed by irradiating ultraviolet light at least tothe main seal from the direction horizontal or diagonal to the substratesurface. If the height of the frame-shape structure is equivalent to thethickness of the panel and the frame-shape structure has theabsorbability for ultraviolet light, a part (particularlyshort-wavelength segment) or all of the ultraviolet light transmittingthe seal is not irradiated on the liquid crystal layer, therebyresulting in the liquid crystal not to be photo-degraded even whenultraviolet light to the main seal from the direction horizontal ordiagonal to the substrate surface is irradiating. Thus, ultravioletlight can be irradiated to the portion previously shaded viewed from thedirection vertical to the substrate, thereby completely curing the seal.(2) Ultraviolet light toward the main seal is irradiated from thedirection horizontal or diagonal to the substrate surface. At the sametime, ultraviolet light is irradiated from the direction vertical to thesubstrate surface as well. Ultraviolet light can be most easilyirradiated from these directions ultraviolet light is absorbed by theresin and becomes low in intensity of illumination if being apart fromthe irradiated surface and depending on a material of the seal, asufficiently cured substance may not be obtained when ultraviolet lightis irradiated only from the above directions. This is because a sealcomponent low in reactivity is more difficult to be cured at lowintensity of illumination. Accordingly, such a seal is irradiated fromthe said directions as well as from the direction vertical to thesubstrate surface. Since the intensity of illumination is hardly reducedin the direction vertical to the substrate surface where the thicknessof the seal film is thin, the seal component low in reactivity is curedand the sufficiently cured substance can be obtained.(3) By irradiating ultraviolet light to the main seal from the directiondiagonal to the substrate, the ultraviolet light is reflected to theshaded portion viewed from the direction of irradiation by a reflectionfilm formed in the area under the main seal. When a seal coatingposition is apart from the side of the substrate, the main seal is alsoon other position besides the side of the substrate as in gang printing,or a dummy seal is between the side of the substrate and the main seal,the seal can not be completely cured by only irradiating ultravioletlight from the said direction. Accordingly, if the ultraviolet light isirradiated from outside the main seal to the said direction and isreflected by the said reflection film to the shaded portion from thedirection of irradiation, the seal can be completely cured.

Since the reflection film in plane structure generates the areadifficult for ultraviolet light to wraparound depending on the angle ofirradiation, ultraviolet light is required to be reflected to the wholeshaded portion by taking a broad angle of irradiation. Accordingly, if aconcavo-convex structure is provided under the said reflection film sothat the reflected light has directivity by controlling the angle ofinclination, the ultraviolet light at a predetermined angle ofirradiation can be efficiently reflected to the shaded portion, therebyeliminating the requirement of the broad angle of irradiation asdescribed above.

(4) The reflection film and a metal film for the TFT substrate areformed together. When a gate bus line or data bus line is formed on theTFT substrate, generally a metal such as Al (aluminum) and the like isused for forming a film. If the metal film is also formed together inthe area coating the seal at this time, a new process is not required tobe added. In this case, ultraviolet light is irradiated from the CFsubstrate side and is reflected on the metal film on the TFT substrate.(5) Even if a reflection substance having the concavo-convex structurein the area to be a the substrate stage and at the same time under themain seal is provided when the irradiation of ultraviolet light isperformed and the angle of inclination of the reflection substance iscontrolled, the ultraviolet light can be effectively reflected to theshaded portion. In this case, although the concavo-convex structureaccording to the seal pattern is required to be structured, an advantageof not requiring to construct a concavo-convex structure or a reflectionfilm for each substrate is generated. Accordingly, the ultraviolet lightat the predetermined irradiation angle can be efficiently reflected tothe shaded portion without adding a new process.(6) Particles dispersing ultraviolet light in the main seal as a measureto irradiate ultraviolet light to the main seal in the directionhorizontal or diagonal to the substrate surface are scattered and theultraviolet light is scattered to the predetermined directions by thesubject particles. Particle in an order of micron or submicron such as afiller is selected as the particle dispersing ultraviolet light to givedispersability by coating the surface with a metal film or an oxidedmetal film. When ultraviolet light is irradiated to these particles, allor a part of the ultraviolet light is dispersed and spread to thepredetermined directions.(7) The frame-shape structure and a color plate for the CF substrate areformed together and the color plate is laminated in the area forming theframe-shape structure. Although colored resins of R, G and B are usedfor the CF color plate, the colored resin hardly transmits ultravioletlight. Formation of the color plate to the CF substrate is performed bysequentially patterning the colored resin to each color-plate area byphotolithography process. If each color plate is also patterned andlaminated in the area forming the structure at this time, the structurecan be formed without adding a new process.(8) The main seal is formed at a position where the internal peripheryof the main seal is adjacent to the external periphery of theframe-shape structure after attaching the substrates so that theinternal periphery of the main seal and the external periphery of theframe-shape structure are adhered. Thus, the fixed surfaces of the mainseal is made on the three surfaces, interface the upper and lowersubstrates and the structure, thereby increasing the adhesive strength.

Further, even if the liquid crystal expands or contracts due tovariations of temperature, the frame-shape structure is fixed on theopposite substrate side via the main seal and the panel thickness of thestructure portion does not vary. Thus, the liquid crystal and the sealcompletely do not make contact after attachment of the substrates aswell and spreading contaminated substances from the liquid crystal canbe prevented.

(9) The liquid crystal display is fabricated by instilling using theabove methods. In instillation, since the seal is cured after liquidcrystal is injected, improvement effects according to the above methodsare significant. In other words, since the shaded portion of the sealremains uncured, the seal component is eluted into liquid crystal,thereby reducing the voltage retention ratio at the edge of the seal.Further, if ultraviolet light is irradiated to the direction horizontalor diagonal to the substrate surface in order to cure the shadedportion, the liquid crystal layer is also irradiated by the ultravioletlight, thereby resulting in photo-degradation of the liquid crystal.Thus, if ultraviolet light is irradiated after forming the frame-shapestructure hardly transmitting the ultraviolet light adjacent to theuncured area, the above disadvantages generated by instillation can beimproved.

Since the above problems are solved according to this embodiment, theyield of the liquid crystal display fabricated by UV press andinstillation is improved. Particularly in instillation, since the sealis cured after liquid crystal is injected, an employment of thisembodiment contributes tremendously to practical applications ofinstillation. The liquid crystal display and a fabrication methodthereof according to this embodiment are described below using examples.

Example 1

As shown in FIG. 17, the frame-shape structure 12 equivalent to thepanel in thickness is formed using a black-color resin on the BM 8 inthe area inside the main seal 6 and at the same time outside the displayarea on the CP substrate 4. After forming the frame-shape structure 12,the alignment film (not shown in the diagram) is coated on the CF/TFTsubstrates 4 and 16, the main seal 6 made of an epoxy-acrylate-typeultraviolet-light-curing resin is coated at the CP substrate 4 side andthe substrates are attached by instillation. In other words, the liquidcrystal 22 with the required volume amount obtained from the internalperipheral side of the frame-shape structure 12 and the thickness of thepanel is dropped in the display area and the substrates attachment isperformed in a vacuum. Then, the atmospheric pressure is restored andliquid crystal instillation and creation of the gap are performed. Afterconfirming the substantial spreading of the liquid crystal 22 in thedisplay area subsequent to creating the gap, the main seal 6 is cured byirradiating ultraviolet light from the side of the substrate to thedirection horizontal to the substrate surface. After performing theisotropic-treatment which heats these attached substrates at 120° C. forone hour, the substrates are scribed and broken and the liquid crystalpanel is obtained. The obtained liquid crystal panel is provided to thelighting test and the seal peeling test. Further, as Comparison Example1, the frame-shape structure formed using the transparent resin isformed and the liquid crystal display panel which cures the main seal isstructured by irradiating ultraviolet light from the direction verticalto the substrate surface, and the similar tests are performed. Resultsof the lighting test and the seal peeling test of Example 1 andComparative Example 1 as well as other examples and comparative examplesare shown in Table 8.

Example 2

As shown in FIG. 18 a, an epoxy-type ultraviolet-light-curing resin isselected for the main seal 6 and creation of the gap are performed byattachment using the similar technique to Example 1. As shown in FIG. 18a, since the thickness of the main seal 6 is as thin as 4-5 μmconforming with the width of the main seal 6 which is approximately 1 mmin the direction of the substrate surface as shown in FIG. 18 b, whilethe luminous intensity in the direction vertical to the substratesurface hardly varies, the luminous intensity in the horizontaldirection gradually reduces. Considering the above, the main seal 6 iscured by irradiating the ultraviolet light from the side of thesubstrate to the direction horizontal to the substrate surface as wellas from the direction vertical to the substrate surface.

The similar treatments and tests to Example 1 are performed for thefollowing. Further, as Comparative Example 2, the liquid crystal displaypanel is structured where the main seal 6 is cured by irradiatingultraviolet light only from the direction horizontal to the substratesurface, and the similar tests are performed. Results of the lightingtest and seal peeling test of the Example 2 and Comparative Example 2are shown in Table 8 as well as other examples and comparative examples.

Example 3

As shown in FIG. 19, a reflection film 152 is formed by depositing Al inthe main seal 6 area on the TFT substrate 16 and at the same time in thearea to be under the main seal 6. After forming the reflection film 152,creation of the gap is performed by attaching the substrates using thesimilar technique to Example 1. Then, ultraviolet light is irradiatedfrom outside the main seal 6 to the direction diagonal to the substratesurface, the ultraviolet light is reflected to the shaded portion by thereflection film 152 and the main seal 6 is cured. At this time, a broadangle of irradiation is taken so that the ultraviolet light is reflectedto the whole shaded portion. The similar treatments and tests to Example1 are performed for the rest. Results of the lighting test and sealpeeling test of Example 3 are shown in Table 8 as well as other examplesand comparative examples.

Example 4

As shown in FIGS. 20 a and 20 b, a concavo-convex structure 154 isformed using a resistive resin in the main seal 6 area on the TFTsubstrate 16 and at the same time in the area to be under the main seal6 so that the angle of inclination of the structure is equal to 15degrees. Next, a reflection film 34 is formed in the subject areatogether with depositing Al on the TFT substrate. After forming thereflection film 34, creation of the gap is performed by attaching thesubstrates using the similar technique to Example 1. Then, ultravioletlight is irradiated from outside the main seal 6 to the direction 60degrees diagonal to the substrate surface and is reflected by thereflection film 34 to the direction vertical to the substrate surface,thereby curing the main seal 6. The similar treatments and tests asExample 1 are performed for the rest. Results of the lighting test andseal peeling test of Example 4 are shown in Table 8 as well as otherexamples and comparative examples.

Example 5

As shown in FIGS. 21 a and 21 b, a concavo-convex structure 38 is formedin the area to be lower part of the main seal 6 on the substrate state36 made of stainless steel so that the angle of inclination of thestructure is equal to 15 degrees. The concavo-convex structure 38 isformed by creating inverted triangle-shape grooves in the area which isthe lower part of the main seal 6 on the substrate state 36 so that theconvex portion is level with the upper surface of the substrate stage36. Lamination of the substrates and creation of the gap are performedby the similar technique to Example 1. Then, the attached substrates arearranged on the substrate stage 36, ultraviolet light is irradiated fromoutside the main seal 6 to the direction 60 degrees diagonal to thesubstrate surface and is reflected to the vertical direction to thesubstrate surface by the concavo-convex structure 38 formed on thesubstrate stage 36, thereby curing the main seal 6. The similartreatments and tests to Example 1 are performed for the rest. Results ofthe lighting test and seal peeling test of Example 5 are shown in Table8 as well as other examples and comparative examples.

Example 6

Dispersion-type particles 40 depositing an Au layer 44 on the surface ofa resin filler 42 having particles of 1 μm in diameter in average asshown in FIG. 22 b is added by the amount of 0.1 wt % in the main seal 6as shown in FIG. 22 a. Lamination of the substrates and creation of thegap using this main seal 6 are performed by the similar technique toExample 1. Then ultraviolet light is irradiated from the directionvertical to the substrate surface and is dispersed by thedispersion-type particles 40 to the direction horizontal or diagonal tothe substrate surface, thereby curing the main seal 6. The similartreatments and tests to Example 1 are performed for the rest. Results ofthe lighting test and seal peeling test of Example 6 are shown in Table8 as well as other examples and comparative examples.

Example 7

As shown in FIG. 23, a frame-shape structure 156 equivalent to the panelin thickness is formed in the area inside the main seal 6 and at thesame time outside the display area together with the formation of thecolor plates on the CP substrate 4. The frame-shape structure 156 isformed by laminating the CP color plates. After forming the frame-shapestructure 156, attachment of the substrates and creation of the gap areperformed by the similar technique to Example 1. Then, ultraviolet lightis irradiated from the side of the substrate to the direction horizontalto the substrate surface and the main seal 6 is cured. The similartreatments and tests to Example 1 are performed for the rest. Results ofthe lighting test and seal peeling test of Example 7 as well as otherexamples and comparative examples are shown in Table 8.

Example 8

As shown in FIG. 24, the main seal 6 is formed at a position where theinternal periphery of the main seal 6 is adjacent to the externalperiphery of the frame-shape structure 12 after attaching thesubstrates. Lamination of the substrates and creation of the gap areperformed by the similar technique to Example 1. Then, ultraviolet lightis irradiated from the side of the substrate to the direction horizontalto the substrate surface as well as from the direction vertical to thesubstrate surface, thereby curing the main seal 6. The similartreatments and tests to Example 1 are performed for the rest. Results ofthe lighting test and seal peeling test of Example 8 are shown in Table8 as well as other examples and comparative examples.

TABLE 8 Table 8 Results of lighting test and seal peeling test ofExample 1 through 7, Comparative Example 1 and 2 Lighting test at theEdge of Seal (3 V, 1 Hz Storage Drive) Before After Seal Peeling TestHeat Heat Strength Treatment Treatment (kgf/mm) Finding Example 1 ◯ ◯2.0 Δ Comparative ◯ X 1.5 X Example 1 Example 2 ◯ ◯ 2.5 ◯ Comparative ◯◯ 1.5 X Example 2 Example 3 ◯ ◯ 2.5 ◯ Example 4 ◯ ◯ 2.5 ◯ Example 5 ◯ ◯2.5 ◯ Example 6 ◯ ◯ 2.5 ◯ Example 7 ◯ ◯ 2.0 Δ Example 8 ◯ ◯ 3.0 ⊙

In Table 8 showing the results of lighting test and seal peeling test ofExample 1 through 7 and Comparative Example 1 and 2, judgments areindicated by X for having a problem in strength, Δ for being a less thanadequate heat-cured seal although having no problem, ◯ for beingequivalent and ⊙ for being more than equivalent.

While there is no problem in either the lighting test or the sealpeeling test in Example 1 through 7, problems occur in the lighting testafter the heat treatment and in strength of the seal peeling inComparative Example 1 and a problem occurs in strength of the sealpeeling in Comparative Example 2. Since ultraviolet light is irradiatedfrom the direction vertical to the substrate surface in ComparisonExample 1, the seal remains uncured in the area shaded by the BMpicture-frame. Although elution of the uncured component is suppressedby the frame-shape structure equivalent to the cell gap before the heattreatment, the liquid crystal expands and flows over the frame-shapestructure after the heat treatment due to variations of temperature, andtherefore the uncured component is eluted in the liquid crystal and thevoltage retention ratio is reduced. Seal peeling also begins from theshaded portion and the seal has been peeled at 1.5 kgf/mm by stressconcentrating in the uncured portion.

An epoxy-type ultraviolet-light-curing resin is used in ComparisonExample 2. The subject resin requires greater luminous intensity thanthe epoxy acrylate type ultraviolet curing resin in Example 1.Accordingly sufficient luminous intensity can not be obtained only ifirradiated from the side face of the substrate to the directionhorizontal to the substrate surface and the subject resin has peeled at1.5 kgf/mm. However, if ultraviolet light is also simultaneouslyirradiated from the direction vertical to the substrate surface as inExample 2, sufficient peeling strength can be exhibited.

The peeling strength is greatest in Example 8 among the examples. Thisis owing to the fact that three surfaces which are the interfaces of theupper and lower substrates and the interface of the frame-shapestructure become the fixed surfaces F.

According to this embodiment, the liquid crystal display panel withimproved yield owing to UV press and instillation can be fabricated.

It will be noted that when the bus line is formed by a Ti/Al laminationlayer as an example of a variation of this embodiment, if Ti is removedonly at portions reflecting UV, concavo-convex is naturally formed onthe Al surface by heat in the fabrication process of TFT (difference inlevel of Ti is insignificant and the reflection ratio is alsoinsignificant). Accordingly, ultraviolet light may be reflectedutilizing this and be incident upon the main seal 6.

A liquid crystal display and a fabrication method thereof according to aseventh embodiment are described with reference to FIG. 25 a throughFIG. 31 c. Although a heat-curing resin is usually used for the mainseal of the liquid crystal display panel, the curing rate of theheat-curing resin is slow and ultraviolet-light-curing resin is used totemporarily fasten in order to avoid misalignment. However, since theefficiency of operation of this temporary fastening process is poor, amethod is proposed in Japanese Laid Open Patent Application No. 5-333351to coat conductive-type ultraviolet-light-curing resin mixing conductiveparticles in circular shape at four corners of the external peripheryside of the main seal and temporarily fasten with a transfer seal.

Further, since UV press and instillation require to cur the main seal ina short period of time, the ultraviolet-light-curing resin or anultraviolet-light plus heat-curing resin is used for the main seal.Since these resins cure quickly, these resins have few misalignment anddo not require temporary fastening. FIG. 25 a shows a state in whichstress is applied to a corner portion of the liquid crystal displaypanel using the main seal 6 containing, for example,ultraviolet-light-curing resin. The ultraviolet-light-curing resin orultraviolet-light plus heat-curing resin is weak in peeling strength incomparison with the heat-curing resin, and as shown in FIG. 25 b,interface peelings β with the substrate are generated at the cornerportions of the main seal 6 where stress is concentrated and peeling bycohesion α is generated in the main seal 6 itself.

Furthermore, as shown in FIG. 26, the picture frame 8 of the blackmatrix (BM) is formed in the fringe periphery portion of the liquidcrystal display panel, and if there is no margin at a position coatingthe main seal 6, the shaded area y shaded by a part of the cornerportion of the main seal 6 overlapping with the end of the BM pictureframe 8 is generated and curing defects occur. The peeling strength ofthe main seal 6 is reduced in this shaded area γ and at the same timethe seal remains uncured and elutes into the liquid crystal, therebyresulting in a reduction of the voltage retention ratio of the liquidcrystal.

In this embodiment, the above problems are solved by using the followingmethods:

(1) In the liquid crystal display panel using theultraviolet-light-curing resin or the ultraviolet-light plus heat-curingresin for the main seal, an interconnecting structure being adjacent tothe seal corner and having the peeling strength greater than that of themain seal in the area outside the main seal and at the same time insidethe end of the CF substrate. A circular arc (R) is provided at the sealcorner in order to make the width of the lines even at the peripheryportion of the seal. However, since the shape of the substrate isrectangular, an air gap is created between the seal and the end of thesubstrate at the seal corner. If the interconnecting structure havingthe peeling strength greater than that of the main seal is partiallyarranged, the peeling strength of the seal corner is more than equal tothe peeling strength of the heat-curing resin and seal peeling does notoccur. The object of forming the resin in the above example in thepublication is to prevent misalignment and the object of this embodimentis to prevent the seal peeling.

Therefore, this embodiment differs from the example in the publicationin the points that the conductive-type particles in the interconnectingstructure is not mixed, the interconnecting structure having the peelingstrength greater than that of the main seal is used, and curing of theinterconnecting structure is performed simultaneously or followingthereafter. If the conductive-type particles are mixed in theinterconnecting structure, the transmissivity is reduced. Accordingly,since the peeling strength is reduced in theultraviolet-light-curing-type interconnecting structure, seal peelingcan not be prevented. Further, in the example in the publication, iftemporary fastening can be performed, the peeling strength greater thanthat of the main seal is not particularly required and curing of theresin is performed prior to curing of the main seal.

(2) In the above (1), the above interconnecting structure is arrangedinto a circular shape in the area which is outside the main seal and atthe same time inside the end of the CF substrate. If the shape iscircular, the interconnecting structure can easily be formed by dottingcoating. Further, if there is sufficient space, it is possible to makethe diameters larger by increasing the amount of coating to the extentthe interconnecting structure does not flow beyond the end of the CFsubstrate or to increase the peeling strength by coating a plurality ofpoints.(3) In the above (1), the above interconnecting structure (resin) isarranged in the direction opposing the panel and at the same time in alinear shape in the area which is outside the main seal and at the sametime inside the end of the CF substrate adjacent to the seal corner. Ifcoated in the diagonal direction to the panel, the distance to the endof the CF substrate can be earned and the interconnecting structure cannot easily flow beyond the end of the CF substrate and if the shape islinear, an adhesive area is larger than the circular shape and thepeeling strength can be further increased.(4) In the above (1), the curing contraction rate of the aboveinterconnecting structure is substantially similar to that of the mainseal. Although the curing contraction rate of the interconnectingstructure differs depending on a selected material, the curingcontraction rate for epoxy-type is equal to approximately 3% and thecuring contraction rate for acrylic-type is equal to approximately 6%among polymerized resins. If a material different from the main seal incuring contraction rate is selected for the above interconnectingstructure, distortion is generated in the above area after curing andbecome a cause of cracking or peeling. Therefore, the materialsubstantially equal to the main seal in curing contraction rate isselected for the above interconnecting structure.(5) In the above (1), the curing of the above interconnecting structureis simultaneously performed with or following the main seal. If theabove interconnecting structure is the ultraviolet-light-curing type andis cured prior to curing of the main seal as in the example in thepublication, the adjacent seal corner is partially cured by multiplereflection on the substrate interface. If the main seal is cured instages from the corner to the whole, the residual stress is generatedinside the seal and the peeling strength is reduced. If the aboveinterconnecting structure is the heat-curing type, heating of the abovearea results in heating of the whole substrate as a consequence, theuncured main seal suffers sagging by heat and the shape of the seal isdistorted. Therefore, when the above interconnecting structure is theultraviolet-light-curing type and is cured simultaneously with curing ofthe main seal and when the above interconnecting structure is theheat-curing type and is cured following curing of the main seal, theabove defects do not occur.(6) In the liquid crystal display panel using theultraviolet-light-curing resin for the main seal, the interconnectingstructure being adjacent to the seal corner and having the peelingstrength greater than that of the main seal in the step area formed bythe CP substrate and the TFT substrate is formed. Since the subject areais an area where peripheral terminals are not usually formed, theinterconnecting structure does not interfere with a driving circuit evenif the interconnecting structure is partially arranged in the subjectarea. The same curing as the above (1) can be expected by partiallycoating and curing the interconnecting structure in the subject areaafter the liquid crystal display panel is formed.(7) In the above (1) and (6), the above interconnecting structure isformed only in the area above the peripheral terminal region. Terminalsconnecting a driving element to a driving circuit are formed in theexternal peripheral portion of the TFT substrate. Since the peripheralterminals are exposed outside the end of the CF substrate by a margin(several mm) to connect the driving circuit, seal peeling is easilygenerated from a non-terminal region because when stress is applied tothe peripheral terminals, the TFT substrate is considerably distortedand the stress is concentrated on the seal/substrate interface, andbecause the distance to the main seal and the stress point islengthened, the stress is amplified by “the principle of the lever”. Onthe contrary, since the upper and lower substrates are level in thenon-terminal region, seal peeling hardly occurs. Accordingly, if theinterconnecting structure is arranged only in the area around theperipheral terminals, seal peeling can be effectively suppressed.(8) In the above (1) and (6), a polymerized resin for theinterconnecting structure. As the polymerized resin is also coated tothe main seal, the polymerized resin is superior in coatability andstability of the shape and is also high in adhesive strength to thesubstrate. Since the interconnecting structure is arranged outside themain seal, the interconnecting structure is not affected bycontamination of liquid crystal, and any of theultraviolet-light-curing-type, the heat-curing-type or theultraviolet-light plus heat-curing-type polymerized resin can be used aslong as the polymerized resin has the peeling strength greater than thatof the main seal.(9) In the liquid crystal display panel using theultraviolet-light-curing resin or the ultraviolet-light plus heat-curingresin for the main seal, adjacent to the seal corner, an L-shapestructure corresponding to the shape of the corner of the BM pictureframe with the height equivalent to the width of the panel is arrangedin the area which is inside the main seal and at the same time outsidethe display area. Since the BM picture frame is formed in the fringeperiphery portion of the liquid crystal display panel, if there is nomargin at a position the seal is coated, a part of the seal corner isshaded by overlapping with the end of the BM picture frame, therebyresulting in the curing defects after substrate attachment. Accordingly,if adjacent to the seal corner, the L-shape structure corresponding tothe shape of the corner of the BM picture frame with a height equivalentto the width of the panel is formed in the area which is inside the mainseal and at the same time outside the display area, the seal is blockedby the structure and can not flow inside beyond the structure even ifthe seal is coated after attachment so that the part of the seal corneroverlaps with the end of the BM picture frame. The position to form thestructure may be selected either outside or level with the end of the BMpicture frame, or inside the end of the BM picture frame by thewraparound amount of light depending on the kind of ultraviolet lightirradiation (either parallel light or dispersed light) and thesensitivity of the ultraviolet light of the main seal.(10) In the above (9), the structure is formed with a material whichdoes not transmit a part or all of the ultraviolet light, and the sealcuring is performed by irradiating ultraviolet light only in the sealcorner from the direction diagonal to the substrate surface. Ifultraviolet light is irradiated from the direction diagonal to thesubstrate, curing can be accomplished to a considerable depth (˜0.5 mm)utilizing multiple reflection on the substrate interface even if theseal corner is shaded by the end of the BM picture frame. However, theultraviolet light transmitting the main seal is also irradiated to theliquid crystal, thereby resulting in a photo-degradation and a reductionof the retention in the vicinity. Accordingly, if the structure isformed with the material which does not transmit a part or all of theultraviolet light, the above defects do not occur and the shaded portionof the seal corner can be effectively cured utilizing multiplereflection.(11) The liquid crystal display panel is fabricated by instillationusing the above (1) through (10). Although the ultraviolet-light-curingresin or the ultraviolet-light plus heat-curing resin is weak in peelingstrength in comparison with the heat-curing resin, the peeling strengthcan be improved by increasing the amount of ultraviolet lightirradiation or by increasing the amount of the heat-curing component tobe added. However, in instillation, since curing of the seal isperformed after injecting the liquid crystal, the liquid crystal isphoto-degraded or the retention adjacent to the seal is reduced due toelution of the heat-curing component if the above treatment is employed.Further, when a part of the seal corner is shaded by overlapping withthe end of the BM picture frame after attachment, the peeling strengthis reduced and at the same time the uncured seal elutes into the liquidcrystal, thereby a resulting in reduction of the voltage retention ratioat the edge of the seal.

Accordingly, if the liquid crystal display panel is fabricated byinstillation using the above methods of (1) through (10), the abovedefects do not occur and effects of improvement are significant.

The yield of the liquid crystal display panel fabricated by the UV pressand instillation is improved by this embodiment. Particularly, ininstillation, since the curing of the seal is performed after injectingthe liquid crystal, employment of this embodiment contributestremendously to practical application of instillation. The liquidcrystal display and the fabrication method thereof according to thisembodiment are described below using examples.

Example 1 and 2

Example 1 is described with reference to FIGS. 27 a through 27 c. FIG.27 a shows a whole liquid crystal display panel and FIG. 27 b shows acorner portion of the liquid crystal display panel. FIG. 27 c shows apoint to pressurize when determining the peeling strength.

An ultraviolet-light-curing resin A (epoxy resin/curing contraction rate3%/made by Three Bond) is used as the main seal 6 and is coated into aframe-shape on the CF substrate 4 on which a CF 11 is formed so that thewidth of the line is equal to 1 mm after attaching the substrates.Sequentially, interconnecting structures 160 a, 160 b and 160 c made ofa heat-curing-type resin (epoxy reins/curing contraction rate 3%/made byMitsui Kagaku) are coated into a circular shape in the area which isadjacent to the corner portion of the main seal 6, outside the main seal6 and at the same time inside the end of the CF substrate 4 so that thediameter is equal to 1 mmφ after attaching the substrates.

FIG. 28 shows Example 2. In Example 2, the interconnecting structure 160a which is the same material as in Example 1 is coated in the directionopposing the panel and at the same time into a linear shape so that thewidth of the line is equal to 1 mm and the length is equal to 2 mm.Further, in Example 1 and 2, since the peripheral terminals are on eachvertical and horizontal side of the TFT substrate 16, theinterconnecting structures 160 a through 160 c are coated in the area (3points) around the peripheral terminals.

Next, the liquid crystal display panel is fabricated by instillation.The required amount of liquid crystal obtained from the measurement ofthe internal periphery of the seal and the thickness of the panel isdropped in the frame-shape pattern of the main seal 6 and attachment isperformed in a vacuum. Subsequently, atmospheric pressure is restoredand injection of liquid crystal and creation of the gap are performed.After the gap is created, the main seal 6 is cured by irradiatingultraviolet light from upper part of the substrate surface. The attachedsubstrates are heated at 120° C. for one hour and the curing of theinterconnecting structure 160 and isotropic (realignment) treatment ofthe liquid crystal are performed. After that, the liquid crystal displaypanel is obtained by cutting the substrates. Further, the liquid crystaldisplay panel (Conventional Example 1) without the interconnectingstructure is also fabricated by the similar technique.

Measurement of the peeling strength is performed separately for theresin unit and the liquid crystal display panel. For the measurement ofthe resin unit, the main seal 6 or the interconnecting structure 160 iscoated on the center of the glass substrate equal 50 mm×20 mm in sizeinto a circular shape so that the diameter is 1 mmφ after attaching thesubstrates, and is attached into a cross shape by the glass substratewith the same size and is cured after the gap is created. An area 1 mminside the end of the glass substrate is pressurized toward lowerdirection by a force gauge and the pressure completely peeling the mainseal 6 or the interconnecting structure 160 is read. For the measurementof the liquid crystal display panel, the CF substrate 4 is arranged ontop, the TFT substrate is arranged at bottom, an area 1 mm inside (referto FIG. 27 c) the end corner of the TFT substrate 16 is pressurizedtoward lower direction by the force gauge, and the pressure completelypeeling the interconnecting structure 160 or the main seal 6 is read.

As a result, the peeling strength of the ultraviolet-light-curing resinA used for the main seal 6 is equal to 1.6 kgf/mm and that of theheat-curing resin used for the interconnecting structure 160 is equal to2.5 kgf/mm. Further, the peeling strength of the liquid crystal displaypanel in Example 1 is equal to 3.0 kgf/mm, that in Example 2 is equal to3.5 kgf/mm, and that in Conventional Example 1 is equal to 1.8 kgf/mm.The peeling strength of the liquid crystal display panel is required tobe a value more than the maximum load on the peripheral terminals in theunitizing process and the value is usually required to be more than 2.0kgf/mm considering the load when replacing a polarizing plate and theattracting force of the driving circuit. In Conventional Example 1,since this standard value is not fulfilled, the yield of fabrication isreduced due to the seal peeling. Since the peeling strengths in Example1 and 2 exceed that of the conventional example and fulfill the standardvalue, therefore seal peeling does not occur.

Example 3

Example 3 is described with reference to FIGS. 29 a and 29 b. Theultraviolet-light-curing resin A (epoxy resin/curing contraction rate3%/made by Three Bond) is used for the main seal 6 and coated into aframe shape on the CF substrate 4 so that the width of the line is equalto 1 mm after attaching the substrates. Sequentially, the liquid crystaldisplay panel is fabricated by instillation. After fabricating theliquid crystal display panel, the diameter is equals to 2 ml andcontacts with both of the substrates so that an interconnectingstructure 162 made of an ultraviolet-light-curing resin B (epoxyresin/curing contraction rate 3%/made by Three Bond) is coated into acircular shape in a step area 164 (refer to FIG. 29 b) formed by the CFsubstrate 4 and the TFT substrate 16 adjacent to the corner portion ofthe main seal 6. It will be noted that since the peripheral terminals 2are also on each vertical and horizontal side on the TFT substrate 16 inthis example as in Example 1, the interconnecting structure 162 iscoated only in the area (three points) of two sides of the peripheralterminals and only the interconnecting structure 162 is spot-irradiatedby ultraviolet light and cured. Measurement of the peeling strength issimilar to Example 1 and 2.

As a result of the measurement, the peeling strength of theultraviolet-light-curing resin A used for the main seal 6 is equal to1.6 kgf/mm and that of the ultraviolet-light-curing resin B used for theinterconnecting structure 162 is equal to 2.0 kgf/mm. The differencebetween the ultraviolet-light-curing resins A and B is that while theamount of addition of multi-functional component or low-molecularcomponent in A is reduced considering the contaminatibility to theliquid crystal, the amounts of those in B are increased to enhance thepeeling strength since B does not make contact with the liquid crystal.Although the above components are more likely to contaminate the liquidcrystal since those components are high in polarity and solubility,those components have a function to increase the peeling strength ofresin. Further, the peeling strength of the liquid crystal display panelin Example 3 is equal to 2.3 kgf/mm and that of the conventional exampleis equal to 1.8 kgf/mm. Since the peeling strength of Example 3 exceedsthat of Conventional Example 1 and fulfills the standard value, sealpeeling does not occur.

Example 4

This example is described with reference to FIGS. 30 a and 30 b. Anultraviolet-light-curing resin C (epoxy acrylate resin/curingcontraction rate 6%/made by Three Bond) is used for the main seal 6 andcoated into a frame shape on the CF substrate 4 so that the width of theline is equal to 1 mm after attaching the substrates. Sequentially, aninterconnecting structure 164 made of the ultraviolet-light-curing resinC is coated into a circular shape in the area outside the main seal 6and at the same time inside the end of the CF substrate 4 adjacent tothe corner portion of the main seal 6 so that the diameter is equal to 1mm+after attaching the substrates.

Further, as Comparative Example 1, an interconnecting structure 164 madeof the ultraviolet-light-curing resin A (epoxy resin/curing contractionrate 3%/made by Three Bond) is coated in the similar manner. Then, theliquid crystal display panel is fabricated by liquefactional injection.

As a result, the peeling strength of the ultraviolet-light-curing resinC used for the main seal 6 is equal to 1.6 kgf/mm and that of theultraviolet-light-curing resin A used for the interconnecting structure164 is equal to 1.6 kgf/mm. Since the ultraviolet-light-curing resin cand A are different resins, the curing contraction rates are different.Further, the peeling strength of the liquid crystal display panel ofExample 4 is equal to 2.2 kgf/mm and that of the comparative example isequal to 1.8 kgf/mm, and in Comparative Example 1 as shown in FIG. 30 b,cracks 166 are generated prior to the peeling test in the main seal 6side where the curing contraction rate is high. Since the peelingstrength of Example 4 exceeds those of Conventional Example 1 andComparative Example 1 and fulfills the standard value, seal peeling doesnot occur.

Example 5

Example 5 is described with reference to FIGS. 31 a through 31 c. Asshown in FIG. 31 a, an L-shape structure 166 corresponding to the shapeof the corner portion of the BM picture frame 8 is formed using a resist(made by Shipley) in the area inside the main seal 6 and at the sametime outside the display area on the CF substrate 4 adjacent to thecorner portion of the main seal 6. The structure 166 being equal to 5 mmin length, 0.7 mm in width and 4 μm in height (equivalent to thethickness of the panel) is formed at a position 0.3 mm inside from theexternal periphery of the BM picture frame 8.

An ultraviolet-light plus heat-curing resin (partially acrylic epoxyresin/curing contraction rate 4%/made by Kyoritsu Kagaku) is used forthe main seal 6 and coated into a frame shape on the CF substrate 4 sothat the width of the line is equal to 1 mm after attaching thesubstrates. The main seal 6 is coated so that the internal periphery ofthe seal precisely contacts with the external periphery of the BMpicture frame 8. Then, the liquid crystal display panel is fabricated byinstillation.

Further, the liquid crystal display panel (Conventional Example 2 and 3)without the structure 166 is also fabricated in the similar technique.After irradiating ultraviolet light from upper part of the substratesurface in Example 5 and Conventional Example 3, as shown in FIG. 31 b,only the corner portion of the main seal 6 is spot-irradiated byultraviolet light from the direction 45 degrees diagonal to thesubstrate surface and the main seal 6 is cured. In addition tomeasurement of the peeling strength, in order to examine the shieldingeffect of ultraviolet light by the structure 21, transmissioncharacteristics of the ultraviolet light and when the resist is formedon the glass are measured.

As a result, the peeling strength of the ultraviolet-light plusheat-curing resin used for the main seal 6 is equal to 2.0 kgf/mm.Further, the peeling strength of the liquid crystal display panel ofExample 5 is equal to 2.3 kgf/mm, that of Conventional Example 2 isequal to 1.8 kgf/mm, and that of Conventional Example 3 is equal to 2.3kgf/m. When the lighting tests are performed for those liquid crystaldisplay panels at an half tone (60 Hz, 3V short wave applied),irregularities in brightness occur in the seal corner in ConventionalExample 2 and 3 due to a reduction of retention ratio. The reduction ofthe retention ratio is attributed to the curing defect of the shadedportion 168 in Conventional Example 2 and photo-degradation of theliquid crystal in Conventional Example 3. However, the peeling strengthin Example 5 fulfills the standard value and irregularities inbrightness due to a reduction of the retention ratio does not occur.

This is owing to irradiation of ultraviolet light from the directiondiagonal to the substrate and wraparound of the ultraviolet light to theshaded portion 168 and also the resist absorbing the harmfulultraviolet-light wavelength to liquid crystal. FIG. 31 c is a graphshowing the transmission characteristics of ultraviolet light of glassand glass plus resist. The transmission characteristics of ultravioletlight in FIG. 31 c indicates that harmful wavelength band (shortwavelength side from 334 nm) to liquid crystal is reduced by the glassplus resist (curved line α) to less than ¼ of that of the glass (curvedline β).

Since the liquid crystal display panel having an excellent yield can befabricated by UV press and instillation according to this embodiment,cost reduction of the liquid crystal display panel can be furtherachieved.

The liquid crystal display and the fabrication method thereof accordingto an eighth embodiment of the present invention are described withreference to FIG. 32 a through FIG. 35. First, a schematic structure ofthe liquid crystal display according to this embodiment is describedwith reference to FIGS. 32 a and 32 b. FIG. 32 a typically shows a partof the upper surface of the active matrix-type liquid crystal displaypanel 1 using the TFT for the switching element viewed from the oppositesubstrate side. FIG. 32 b shows a partial cross section cut at a lineA-A of FIG. 32 a. A plurality of gate bus lines G1, G2, . . . Gn(hereinafter, abbreviated as G) extending in horizontal direction on thesubstrate in the diagram are formed in parallel in vertical direction onthe array substrate 16. Further, an insulation film which is not shownin the diagram is formed on the plurality of the gate bus lines G and aplurality of data bus lines D1, D2, DU (hereinafter, abbreviated as D)substantially orthogonal to the gate bus line G are formed on theinsulation film. Each area decided in a matrix shape by the gate busline G and the data bus line D which are orthogonal to each otherbecomes a pixel area and a TFT 13 and a display electrode 14 are formedin each pixel area. A gate electrode of the TFT 13 is connected to apredetermined gate bus line G, a drain electrode is connected to apredetermined data bus line D and a source electrode is connected to thedisplay electrode 14 in the pixel area.

FIG. 32 b shows a cross section along the gate bus line G1, the gate busline G1 is formed on the surface of the array substrate 16 facing theopposite substrate 4, and an alignment film 172 is formed on the topsurface. A common electrode 8 is formed on the surface of the oppositesubstrate 4 facing the array substrate 16 and an alignment film 170 isformed on the top surface.

The opposite substrate 4 formed substantially smaller by approximatelythe width of the terminal portion 2 than the array substrate 16 isarranged facing the array substrate 16 with a predetermined cell gap.The array substrate 16 and the opposite substrate 4 are attached by thesealing material 6 made of the photo-curing resin. The liquid crystal 22is sealed in the area surrounded by the sealing material 6 between thearray substrate 16 and the opposite substrate 4.

A plurality of the gate bus lines G and the data bus lines D extend tothe terminal portion 2 formed in the external periphery of the arraysubstrate 16 and are to be connected to a driving circuit (not shown inthe diagram) arranged externally. An external output electrode 174 isformed in the end portion of each of the gate bus line G and an externaloutput electrode 176 is formed in the end portion of each of the databus line D as well.

The TFT 13 connected to the gate electrode of the subject gate bus linebecomes an “On” state by a scanning signal output to a predeterminedgate bus line G, and the voltage based on a gradation signal outputtedto the data bus line D is applied to the pixel electrode 14. On theother hand, a predetermined voltage is also applied to the commonelectrode 8 on the opposite substrate side so that the liquid crystal 22between the pixel electrode 14 and the common electrode 8 is driven bythe voltage applied to the pixel electrode 14 and the common electrode8.

Now, the liquid crystal display according to this embodiment has adistinctive characteristic in forming a plurality of light-reflectionlayers R in the contacting area of the array substrate 16 and theopposite substrate 4 of the sealing material 6. This light-reflectionlayer R is described with reference to FIGS. 33 a through 33 c. FIG. 33a shows an enlarged block 30 indicated by the dotted line in FIG. 32 a.FIG. 33 b shows a cross section of the panel of the area shown in FIG.33 a. Further, FIG. 33 c shows a cross section of a conventional panelcorresponding to FIG. 33 b for comparison.

As shown in FIGS. 33 a and 33 b, the light-reflection layer R isalternately formed in the sealing material coating area of the arraysubstrate 16 and the opposite substrate 4. A light-reflection layer RLis formed, for example, simultaneously in the sealing material coatingarea on the array substrate 16 by using a metal for forming the gate busline or a metal for forming the data bus line in the area coating thesealing material on the array substrate 16 when forming those bus lines.The light-reflection layer RL is formed in a line-and-space patternparallel to the gate bus line G or the data bus line D and having a longside slightly longer than the width of the area forming the sealingmaterial 6.

On the other hand, a light-reflection layer RU is formed in thecontacting area of sealing material in the opposite substrate 4 side bypatterning a metal layer and has a line-and-space pattern shifted byhalf a pitch from the light-reflection layer RL on the array substrate16 as if filling a space portion (space) of the light-reflection layerRL when attaching the opposite substrate 4 with the array substrate 16.

Therefore, when irradiating UV light for curing the sealing material 6as shown in FIG. 33 b, if a UV light UV1 is entered substantiallyvertical to the surface of the panel from the opposite substrate 4 side,the light. UV is reflected at the light-reflection layer RL on the arraysubstrate 16 and goes back in the sealing material 6 in the subjectarea. Thus, the energy of the light UV1 can be effectively utilized tocure the sealing material 6 of the subject area without waste anddegradation of the liquid crystal 22 can be prevented by quickly curingthe sealing material 6. Similarly, if a UV light UV2 is enteredsubstantially vertical to the surface of the panel from the arraysubstrate 16 side, the light UV2 is reflected at the light-reflectionlayer RU on the opposite substrate 4 and goes back in the sealingmaterial 6 of the subject area. Thus, the energy of the light UV2 can beeffectively utilized to cure the sealing material 6 of the subject areawithout waste and degradation of the liquid crystal 22 can be preventedby quickly curing the sealing material 6.

While the above UV lights UV1 and UV2 are irradiated from both surfacesof the panel, an UV light UV3 may be irradiated diagonally to thesurface of the panel. Although light transmitting through the panelexists in this case, the amount of UV light reflecting once or inplurality at the light-reflection layers RL and RU and transmittingthrough the sealing material 6 can be increased, thereby effectivelyutilizing the energy of the light UV3 to cure the sealing material 6 ofthe subject area without waste and preventing degradation of the liquidcrystal 22 by quickly curing the sealing material 6. It will be notedthat, since the major side of the line-and-space pattern of the lightreflection layers RL and RU are substantially orthogonal to thetraveling direction (same as a moving direction 211 shown in FIG. 108 a)of the UV light source in this embodiment, irradiating the light UV3diagonally to the surface of the panel within the surface created by thenormal line of the surface of the panel and the traveling direction ofthe UV light source is desirable with respect to effectively utilizingirradiation energy. Furthermore, if the previously-described surface canbe slightly inclined assuming the traveling direction of the UV lightsource as an axis, the light UV3 can be irradiated from the center ofthe liquid crystal display portion toward outside the display portion.Thus, the UV light leakage toward the liquid crystal display portionside adjacent to the sealing material 6 can be reduced and degradationof the liquid crystal 22 can surely be.

FIG. 33 c shows UV irradiation according to the conventional liquidcrystal display for comparison. Even if UV irradiation UV4 and UV5 isperformed from the direction substantially vertical to the panel in thestructure of the conventional liquid crystal display, all the light suchas the light UV4, except for reflecting at the external outputelectrodes 174 and 176 of the gate bus line G and the data bus line Dsuch as the light UV5, only once transmits the sealing material 6.Therefore, the energy of the UV light can not be sufficiently utilizedfor curing the sealing material in the conventional liquid crystaldisplay.

Various variations are possible in this embodiment. This embodiment isdescribed assuming that the light-reflection layer R has theline-and-space pattern. However, for example, the widths of the gate buslines G and the data bus lines D in the contacting area of the sealingmaterial 6 on the array substrate 16 may be widened to make thelight-reflection layer RL, and the light-reflection layer RU may beformed in the contacting area of the sealing material 6 on the oppositesubstrate 4 to fill the gap between the light-reflecting layers RL.

Further, in the case of a reflection-type liquid crystal display asshown in FIG. 34, the light-reflection layer R can be arranged betweenthe plurality of the bus lines passing through the contacting area ofthe sealing material 6 on the array substrate (reflection substrate).Thus, in the reflection-type liquid crystal display, by utilizing thereflecting light of the UV light, the energy of the light also can beeffectively utilized for curing the sealing material without waste anddegradation of the liquid crystal 22 can be prevented by quickly curingthe sealing material 6.

Furthermore, as shown in FIG. 35, it is effective to irradiate UV lightgathered by a lens 32 toward the sealing material 6 so that the UV lightdoes not enter the liquid crystal 22. Since the energy of the UV lightcan be concentrated and provided to the sealing material 6 according tothis, time to cure the sealing material can be shortened, therebypreventing the liquid crystal 22 from degradation.

It will be noted that although the sealing material 6 is cured by makinga direct contact on the light-reflection layer R in the aboveembodiment, in order to improve the adhesive ability of the sealingmaterial 6, for example, a silicon oxide film (SiO₂ film) and the likemay certainly be formed on the light-reflection layer R to make thesealing material 6 direct contact with the silicon oxide film.

Example 1

Next, an example of the fabrication method of the liquid crystal displaybased on this embodiment is briefly described with reference to FIG. 32a through 33 c. Further, since the fabrication method of the liquidcrystal display according to this example has a distinctivecharacteristic in reducing degradation of the liquid crystal due to UVirradiation for curing the sealing material so that instillation in thecell process can be performed with certainty, description is omitted forthe similar process to the past among the processes such as the arrayprocess forming a wiring pattern, switching elements and the like on theother glass substrate, the cell process dealing with alignment layertreatment, arranging spacers and the like, or the module processinstalling a driver IC, setting up the back light and the like.

First, for example, the array substrate 16 made of the glass substrateequal to 50 mm×60 mm×0.7 mm is used. When forming the gate bus lines andthe data bus lines on the array substrate 16, the light-reflection layerRL is formed on the contacting area of sealing material 6 by patterningthe metal layer for forming the bus line formed on the whole substratesurface. As the metal for forming the bus line, Cr, Al, Ti and the likecan be used. The light-reflection layer RL is equal to 100 μm in widthand is the line-and-space pattern having the width between the adjacentlight-reflection layers is also equal to 100 μm. On the other hand, onthe opposite substrate 4 side, for example, when forming the blackmatrix (BM: shading film), the light-reflection layer RU is formed inthe contacting area of sealing material 6 by patterning the metal layerfor forming the BM formed on the whole substrate surface. As a metal forforming the BM, Cr can be used. The light-reflection layer RU ispatterned when the opposite substrate 4 is attached with the arraysubstrate 16 so that the light-reflection layer RU shifts by half apitch from the line-and-space pattern of the light-reflection layer RL.Therefore, the light-reflection layer RU also is equal to 100 μm inwidth and the width between the adjacent light-reflection layers is alsoequal to 100 μm.

After forming an alignment film (AL 3506) on the substrate surfaceinside the contacting area of the sealing material 16 of the arraysubstrate and the opposing substrate 4 and performing a rubbingtreatment so that a TN (torsion nematic) liquid crystal layer can beformed, an UV sealing material (made by Kyoritsu Kagaku) 6 is coated onthe opposite substrate 4. After the liquid crystal (FT-5082) 22 isdropped on the array substrate 16 by an instilling equipment which isnot shown in the diagram, both of the substrates 4 and 16 are attached.By irradiating the UV light of 60 mW/cm² in irradiation energy from bothsides of the array substrate 16 and the opposite substrate 4 to thecoating area of the sealing material 6, the sealing material 6 is curedand the panel is completed.

On the other hand, as a comparative example, the UV sealing material 6is coated on the opposite substrate where the light-reflection layer RUis not formed, both substrates are attached after instillation, and thesealing material 6 is cured by performing UV irradiation only from theopposite substrate side. In this case, substantially twice as much asthat of the UV irradiation according to the above example is required inorder to generate a sufficient curing effect.

When ion densities at predetermined areas of the above two panels aremeasured, the ion density of this example is much lower than that of thecomparative example, thereby confirming that damages to liquid crystalcan be substantially reduced by the structure according to thisembodiment.

A liquid crystal display and a fabrication method thereof according to aninth embodiment of the present invention is described with reference toFIG. 36 through FIG. 39 b. FIG. 36 shows a state in which UV irradiationof the sealing material is performed at the end portion of the liquidcrystal panel. As to a point where the sealing material 6 of aphoto-curing type material is provided to seal liquid crystal betweenthe array substrate 16 and the opposite substrate 4, this embodiment issimilar to the conventional liquid crystal display. However, thisembodiment has a distinctive characteristic that an UV light UV6 forcuring the sealing material 6 is a polarized light and, further, thatthe liquid crystal 22 is a material which is not degraded incharacteristics even if the UV6 having polarized light is irradiatedthereon.

FIG. 37 shows the characteristics of two kinds of liquid crystalmaterial (A) and (B). The vertical axis indicates extinction rate andthe lateral axis indicates wavelength. The Δn (optical anisotropy:difference in refractive indexes between extraordinary ray and ordinaryray) of the liquid crystal material (A) is smaller than that of theliquid crystal material (B). As shown in FIG. 37, both liquid crystalmaterials (A) and (B) show high extinction rates in the short wavelengthside and that it is confirmed that the more the Δn is great, the morethe end of extinction is relatively at a high frequency side. This endof extinction is in the ultraviolet light area equal to approximately300 nm to 360 nm in wavelength. Therefore, the larger the refractionindex of the liquid crystal material is, the more ultraviolet light isabsorbed and are more easily changed. In other words, if the UV light isirradiated when the refraction index of a liquid crystal material isreduced, tolerance against the degradation of characteristics due to UVlight can be improved.

For example, as shown in FIGS. 38 a through 38 c, if UV is irradiated sothat a polarizing axis 46 of the polarized UV to be irradiated is inaccordance with the direction of a minor axis of a liquid crystalmolecules 182, the degradation of the liquid crystal 22 can besuppressed. FIG. 38 a shows a part of the area of the liquid crystaldisplay panel viewed from the opposite substrate side. The alignmentfilm formed on the array substrate side, as shown by an arrow 180 of adotted line in the diagram, is performed the rubbing treatment fromupper left to lower right and the alignment film formed on the oppositesubstrate 4 side, as shown by an arrow 178 of a solid line in thediagram, is performed the rubbing treatment from upper right to lowerleft in the direction substantially orthogonal to the arrow 180. As aresult of this rubbing treatment, the liquid crystal molecules 182 ofthe liquid crystal 22, as shown in FIG. 38 b, are arranged adjacent tothe surfaces of both substrate 4 and 16 so that a major axis is twisted90° from the rubbing direction. With respect to such a torsion alignmentas shown in FIG. 38 c, if UV light having the polarizing axis 46 in thedirection orthogonal to the half way of the direction of the major axisof the liquid crystal molecules 182 adjacent to both substrate surfacesshown in FIG. 38 b is irradiated, irradiation in a state that therefraction index of liquid crystal is reduced can be realized.

An example applied to an arrangement of other liquid crystal moleculesis described with reference to FIGS. 39 a and 39 b. FIG. 39 a shows apart of the liquid crystal display panel viewed from the oppositesubstrate side. The alignment film formed on the array substrate 16side, as shown by the arrow 180 of a dotted line in the diagram, isperformed the rubbing treatment from up to down in the diagram, and thealignment film formed on the opposite substrate 4 side, as shown by thearrow 178 of a solid line in the diagram, is performed the subbingtreatment from down to up. As a result of this rubbing treatment, themajor axis of the liquid crystal molecules 182 is an arrangementcontained in a plane vertical to the substrate. In such an alignment, asshown in FIG. 39 b, if UV light having the polarizing axis 48 in thedirection orthogonal to the direction of the major axis of the liquidcrystal molecules 182, irradiation in a state that the refraction indexof liquid crystal is reduced can be realized.

Example 2

A panel by instillation is fabricated by using the similar glasssubstrate to the one in Example 1. The rubbing direction of thealignment film is, as shown in FIG. 39 a, an anti-parallel direction anda liquid crystal cell is homogeneous. A liquid crystal panel irradiatedthe polarized UV having the polarizing axis in the direction of themajor axis of the liquid crystal and the liquid crystal panel irradiatedthe polarized UV having the polarizing axis in the direction of theminor axis of the liquid crystal are fabricated. As a result ofcomparison at predetermined areas, it is confirmed that the voltageretention ratio is higher and the ion density is lower in the liquidcrystal panel irradiated polarized UV having the polarizing axis in thedirection of the minor axis of the liquid crystal.

Thus, according to this embodiment, degradation of the liquid crystal 22can be suppressed in comparison with the case of irradiation of thenon-polarized UV light.

Next, a liquid crystal display and a fabrication method thereofaccording to a tenth embodiment of the present invention are describedwith reference to FIG. 40 through FIG. 42 b. FIG. 40 shows a state inwhich the liquid crystal is vertically aligned due to a verticalalignment film by instilling the liquid crystal 22 of, for example, anegative dielectric anisotropy. In this case, since the major axis ofthe liquid crystal molecules 182 is substantially parallel to theirradiation direction of an UV light UV7 for irradiating the sealingmaterial 6, dependency of polarizing direction against the UV light tobe irradiated can be reduced. Thus, the light UV7 can be non-polarized.

Further, for example, when fabricating a liquid crystal display panelusing the liquid crystal 22 of positive dielectric anisotropy, as shownin FIG. 41 a, an alignment film 50 for a horizontal alignment is formedin the main portion of the display area and adjacent to the sealingmaterial 6 aside from the alignment film 50, a vertical alignment film52 for vertically aligning the liquid crystal is formed. Thus, whenirradiating UV for curing the sealing material 6, even if leaked lightis incident on the liquid crystal 22 adjacent to the sealing material 6,since the major axis of the liquid crystal molecules 182 is parallel tothe irradiation direction of UV light, dependency of polarizingdirection is small, therefore degradation of liquid crystal can besuppressed even with non-polarized UV light.

FIG. 41 b shows a structure of an example of a variation in which thealignment film 50 for horizontal alignment is formed as far as adjacentto the sealing material 6, and the alignment film 52 for verticalalignment is separately formed on the alignment 50 adjacent to thesealing material 6. Further, FIG. 41 c shows a structure of an exampleof another variation in which the alignment film 52 for verticalalignment is formed as far as adjacent to the sealing material 6 and thealignment film 50 for horizontal alignment is separately formed on thealignment film 52.

Furthermore, when the liquid crystal 22 has a positive dielectricanisotropy, by adopting a structure shown in FIGS. 42 a and 42 b,degradation of liquid crystal can be suppressed even if non-polarized UVlight is irradiated. FIG. 42 a shows, when irradiating UV for curing thesealing material, that the liquid crystal molecules 182 adjacent to thesealing material 6 are vertically aligned by applying voltage between adisplay electrode 14 on the array substrate 16 adjacent to the sealingmaterial 6 and a common electrode of an opposite electrode 4 by avoltage supply source 54. Thus, even if leaked light is incident on theliquid crystal 22 adjacent to the sealing material 6 when irradiating UVto cure the sealing material 6, since the major axis of the liquidcrystal molecules 182 is parallel to the irradiation direction of UVirradiation light, dependency of polarizing direction is small,therefore degradation of liquid crystal can be suppressed even if UVlight is non-polarized.

Also, as shown in FIG. 42 b, another electrode 58 electrically isolatedfrom the pixel electrode 14 may be formed in advance on the arraysubstrate 16 adjacent to the sealing material 6, and another electrode60 electrically isolated from the common electrode 8 may be formed onthe opposite substrate 4 adjacent to the sealing material 6. Theelectrodes 58 and 60 are connected to a driving power source 56.

When irradiating UV to cure the sealing material 6, voltage is appliedbetween the electrodes 58 and 60 by the driving power source 56 and theliquid crystal molecules 182 adjacent to the sealing material 6 arevertically aligned. Even if leaked light from UV irradiation is incidenton the liquid crystal 22 adjacent to the sealing material 6, since themajor axis of the liquid crystal molecules 182 are parallel to theirradiation direction of UV irradiation light, dependency of polarizingdirection is small, therefore degradation of liquid crystal can besuppressed even if UV light is non-polarized. If the structures shown inFIG. 41 a through 41 c, and FIG. 42 b are used in a normally white-typeliquid crystal display, the area between the alignment films 52 or thearea between the electrodes 58 and 60 can function as the picture-frameportion of display area.

Example 3

The panel is fabricated by using the similar glass panel andinstillation to Example 1. The alignment film is rubbed as if formingthe TN liquid crystal cell. When both substrates are attached and UVlight is irradiated to the sealing material 6, the liquid crystal 22between the electrodes 58 and 60 is vertically aligned by applyingrectangular wave equal to 5V (30 Hz) to the electrodes 58 and 60 shownin FIG. 42 b and the sealing material 6 is cured. As a result, excellentresults are shown in both voltage retention ratio and ion density incomparison with when voltage is not applied.

Next, a liquid crystal display and a fabrication method thereofaccording to an eleventh embodiment of the present invention aredescribed with reference to FIG. 43 a through FIG. 55. It will be notedthat the structuring elements having the same operation functions as inthe first through tenth embodiments are referred by the same codes andthe descriptions are omitted. In this embodiment, an object is torealize a narrow picture frame and a big effect can be achieved bycombining a reflective type LCD or technology to form CF on the arrayside. Further, this technology can be applied to an instilling method ina fabrication process of a polymer dispersion-type liquid crystaldisplay (PDLC).

In recent years, the PDLC providing a picture display high in brightnesswithout using a polarization plate as in the past is proposed by usingpolymer dispersion-type liquid crystal in which nematic liquid crystalis dispersed and maintained in a polymer having the similar refractionrate to a liquid crystal molecules and performing switching by applyingvoltage between the two substrates sandwiching this polymerdispersion-type liquid crystal. Fabrication methods of this PDLCinclude, for example, a method of making an uniform solution of liquidcrystal and polymerized material, filling up the liquid crystal paneland then phase-separating by photo-polymerization and forming aphase-separated structure.

Usually, since the amount or wavelength of exposure required forpolymerizing liquid crystal and curing a sealing material are different,if UV light required for irradiating the sealing material of aphoto-curing-type resin is irradiated to liquid crystal, the liquidcrystal is inadequately exposed. In this embodiment, a structure and amethod to prevent this are described by using examples. When theinstilling method is used in a fabrication process of the PDLC panel, byintroducing the technique described below, reduction of picture-framewidth of a panel can be realized and at the same time a fabrication lineto fabricate a polymer dispersion-type liquid crystal display by asimple process can be realized.

Although previously explained in the above embodiment, in order torealize a reduction in picture-frame width of a panel in the instillingmethod, forming a sealing material in the BM picture-frame portion onthe color filter (CF) side is essential. In this embodiment, light isirradiated from the array substrate side so that the sealing material atlower part of the BM picture-frame portion can be sufficiently cured. Awraparound phenomenon of the light is generated by a plurality ofwirings formed on the array substrate side and the light is highlyeffectively transmitted in the sealing material. Descriptions based onexamples follow.

Example 4

Example 4 is described with reference to FIG. 43 a through FIG. 46.

UV light is not necessarily required to be irradiated in the whole areaof the sealing material to photo-curing the UV curing-type sealingmaterial 6 coated on the opposite substrate 4. Because, the lightincident upon the sealing material 6 wraparounds other areas than theirradiated area by dispersing and internally reflecting. The distance inwhich the wraparounding of the light can be expected is equal toapproximately 200 μm. Therefore, if a wiring 78 is within 400 μm inwidth (L), the sealing material 6 can be sufficiently cured by theeffects of the wraparounding of the light from both edge of the wiring78.

Further, in order to realize a narrow picture-frame panel, the sealingmaterial 6 is required to be coated so that a part or all of thecontacting area with the substrate of the sealing material 6 overlapsinside the BM picture-frame portion. Usually, the BM picture-frameportion 108 is formed by depositing a low-reflection chrome (Cr) film ora black-color resin on the opposite substrate 4 side where the CF is tobe formed. Since the transmissivity of light at the BM picture-frameportion 108 is extremely small, in order to irradiate UV light to thesealing material 6 overlapping with the bottom of the BM picture-frameportion 108, UV irradiation is performed from the array substrate 16side via the wiring 78 just under the sealing material 6.

FIG. 43 a is an example showing a schematic structure of a part of thecross section at the end portion of the liquid crystal panel. FIG. 43 bis a partial plan view of the end portion of the panel viewed toward thearray substrate surface. In the contacting area of sealing material 6 onthe array substrate 16 which is a transparent glass substrate, thewiring 78 of the TFT (thin film transistor) or formation metal of thegate/drain bus line is used. In the example shown in FIGS. 43 a and 43b, the plurality of the wirings 78 extending along the coating directionof the sealing material 6 are formed in parallel. The wiring 78 is equalto approximately 400 μm in width (L) as described above. The widthbetween the wirings is also equal to approximately 400 μm. The sealingmaterial 6 contacts with the array substrate 16 on the plurality of thewirings 78. The other end of the sealing material 6 contacts with theopposite substrate 4 where the BM picture-frame portion 108 is formed.Approximately 80% of the contacting area at the other end of the sealingmaterial 6 overlaps with the BM picture-frame portion 108. The liquidcrystal 22 is sealed between both substrates. If a UV light UV8 isirradiated from the array substrate 16 side in such a structure, thelight UV8 wraparounds inside the sealing material 6 by the wiring 78, isfurther reflected at the BM picture-frame portion 108 and is dispersedinside the sealing material 6 after a part of the UV light is still morereflected on the back of the wiring 78, thereby sufficiently curing thewhole sealing material 6.

FIG. 44 shows an example of a variation of the wiring 78 shown in FIG.43 b. While the wiring 78 shown in FIG. 43 b has a stripe pattern, awiring 79 shown in FIG. 44 has a structure forming a plurality of shortlight transmission windows in the area where a plurality of wiringsorthogonally cross. The width (L) of the wirings is also equal to 400 μmin this example. A wiring 80 shown in FIG. 45 is also an example of avariation of the wiring 78 and has a formation having a plurality ofwirings bridged over the two wirings formed on the side of thecontacting area of sealing material. The width (L) of each wiring isequal to 400 μm. FIG. 46 shows an example of a variation of the panelshown in FIG. 43 a. The whole contacting area of the sealing material 6on the opposite substrate 4 side overlaps with the BM picture-frameportion 108. By irradiating UV light from the array substrate 16 side,the sealing material can be sufficiently cured in this case as well.

Example 5

Example 5 is described with reference to FIGS. 47 a, 47 b and FIG. 48.

As previously described in the above embodiment, the peaks of brightlines which particularly degrade liquid crystal among the ultravioletlights transmitting the glass substrate are the line j (313 nm) and theline i (365 nm). In the case of a UV incidence from the color filterside, the CF color plate hardly transmits the line j nor the line i andthe BM does not transmit the line nor the line I at all. In short, whenentering the UV light from the array substrate 16 side of thetransmission-type liquid crystal display, the degradation of the liquidcrystal 22 can be prevented by forming the color filter on the arraysubstrate 16 side. Further, in the reflection-type liquid crystaldisplay, a reflection electrode can perform a function of shading tosome extent.

FIG. 47 a is an example showing a schematic structure of a part of thecross section of the end portion of the liquid crystal panel. FIG. 47 bis a partial plan view of the end portion of the panel viewed toward thearray substrate surface. The panel shown in FIGS. 47 a and 47 b forms aCF 82 in the area forming a pixel on the array substrate side.Therefore, by blocking at least the line j and the line i among UVlights, the degradation of the liquid crystal 22 can be prevented. FIG.48 shows a reflection-type liquid crystal display panel utilizing areflection electrode 83 as an UV shading film to block the line j andthe line i. The reflective electrode may be formed on the side where theliquid crystal of the array substrate surface is filled.

Example 6

Example 6 is described with reference to FIG. 49.

When a photo-curing-type liquid crystal 23 is used, conditions for thelight irradiation to the liquid crystal 23 and to the sealing material 6are different. In this example, an UV light UV9 irradiating the sealingmaterial 6 is equal to approximately 1000 mJ/cm² in irradiation energy.Further, an UV light UV10 irradiating the liquid crystal 23 is equal toapproximately 2000 mJ/cm² in irradiation energy without the CF. The UVlight UV9 for curing the sealing material 6 is irradiated from the arraysubstrate 16 side via the wiring 78 and the like. The UV light UV10 forpolymerizing the liquid crystal 23 is irradiated from the oppositesubstrate 4 side. At this irradiation, the color filter may be formed oneither substrates. By separately using the two conditions for theirradiation with the use of separate light sources in this manner,performing of the most adequate curing for each is possible.

Example 7

Example 7 is described with reference to FIG. 50.

By previously performing polymerization of the liquid crystal 23 whichdirectly affects to the display quality of the liquid crystal display,it is possible to prevent curing of the liquid crystal 23 frominadequately starting by light leakage or wraparound of UV light whencuring the sealing material 6. By curing the liquid crystal 23 inadvance, contamination from the uncured sealing material 6 can besuppressed.

Further, a material having a photo-polymerization characteristic or aliquid crystal material mixed with photo-polymerization-type resin maybe used for liquid crystal and a heat-curing-type material may be usedfor a sealing material. In this case, after attaching the twosubstrates, the liquid crystal can be cured by irradiating the UV light,and then heat treatment for the sealing material can be performed. Sincethe liquid crystal is cured in advance, contamination from uncuredsealing material can be also tolerated for a long period of time in thismanner.

Example 8

Example 8 is described with reference to FIG. 51 through FIG. 53.

A distinctive characteristic is that visible light photosensitive-typeresin is used for the sealing material 6. Therefore, in FIG. 51, thesealing material 6 is first irradiated by a visible light NL1 and cured.At this time, even if the liquid crystal 23 is irradiated by the leakedvisible light NL1, since irradiation is off the photosensitive area ofthe liquid crystal 23, a problem does not occur. Next, the liquidcrystal 23 is exposed by irradiating a UV light UV1. At this time, evenif the sealing material 6 is irradiated by the leaked light, curing ofthe sealing material has already been completed, thereby not resultingin any problem. In FIG. 52, the sealing material 6 is irradiated by avisible light NL2 and cured in a reflection-type liquid crystal displayand the like. Then, the liquid crystal 23 is irradiated by an UV lightUV12 from the opposite substrate 4 side and exposed. In FIG. 53, thevisible light photosensitive-type sealing material 6 is used to cure bya natural light.

Example 9

Example 9 is described with reference to FIG. 54.

The liquid crystal display shown in FIG. 54 shows a state in which an UVlight UV13 for curing the sealing material 6 is irradiated from thearray substrate 16 side without specifically limiting the irradiationarea. A filter 90 for reducing the amount of irradiation of the UV lightUV13 is laminated in the area outside the irradiation area for thesealing material 6 on the surface of the light irradiation side of thearray substrate 16. When a difference in condition for exposure betweenthe liquid crystal 23 and the sealing material 6 exists in thewavelength of light, the light can be modulated by using a band-passfilter for the filter 90. When a difference in condition for exposurebetween the liquid crystal 23 and the sealing material 6 exists in theamount of light irradiation, the light can be modulated by using asemi-transmission-type filter for the filter 90. Further, according tothis irradiation method, the UV irradiation for curing the sealingmaterial 6 can be performed from the array substrate 16 side and at thesame time the UV irradiation for the liquid crystal 23 can be performedfrom the opposite substrate 4 side.

Example 10

Example 10 is described with reference to FIG. 55. FIG. 55 shows a statein which a light dispersion member 92 made of glass or film formingirregularities on the surface for dispersing irradiated light isinserted between the light source for irradiation and the attachedsubstrate 62. In this manner, the phenomenon of wraparound of lightalready described in the above example can be effectively generated.

Next, a fabrication method of a liquid crystal display according to atwelfth embodiment of the present invention is described with referenceto FIGS. 56 a and 56 b. In this embodiment, a fabrication of a liquidcrystal display in which peeling of a sealing material is prevented andinstillation in the cell process can be steadily performed is described.

FIGS. 56 a and 56 b show instillation of liquid crystal in the cellprocess for the liquid crystal panel according to this embodiment. FIG.56 a shows a state in which substantially the same amount as liquidcrystals are dropped on the array substrate surface in the sealingmaterial 6 so that distances for dispersion between the adjacent dropsof fluid are substantially the same, and liquid crystals 188 having theamount less than the dropping amount of the liquid crystal 184 aredropped at positions where the dispersion of liquid crystal is sparse inthe external periphery of the liquid crystal 184. With respect to thedropping position of each liquid crystal 184, the distances to positions4 where adjacent liquid crystals 184 are dropped have a relationship ofd1=d2=d3=d4=d5=d6 as shown in the diagram. FIG. 56 b shows a state inwhich the liquid crystals 184 and 188 are dispersed after the arraysubstrate and the CF substrate are attached. As shown in FIG. 56 b, inthis embodiment, a gap 186 at dispersion of liquid crystal after thesubstrates are attached is small and dispersion of liquid crystal can becompleted as little as less than 5 minutes. Therefore, peeling of a sealas in the past does not occur and neither does a leakage of liquidcrystal.

Thus, this embodiment has a distinctive characteristic in varying theamount of liquid crystals 184 and 188 to be dropped depending on adropping position in the fabrication process of the liquid crystaldisplay having the process in which the array substrate 16 and the CFsubstrate 4 are attached after liquid crystal is dropped at a pluralityof positions on the array substrate 16. Further, another distinctivecharacteristic is that liquid crystal is dropped by combining a droppingpattern for deciding the positions to drop the liquid crystal 184 and adropping pattern for deciding the positions to drop the liquid crystal186. In this example, according to the dropping pattern for deciding thedropping positions for the liquid crystal 184, substantially the sameamounts of the liquid crystal are dropped so that the distances fordispersion between the adjacent drops of fluid are substantially thesame and according to the dropping pattern for deciding droppingpositions for the liquid crystal 188, liquid crystal in the amount lessthan the amount of the liquid crystal 184 is dropped in positions wheredispersion of liquid crystal is sparse at the external periphery of theliquid crystal 184.

As explained above, by dividing the dropping amount of liquid crystaland the dropping patterns into at least two kinds and performing liquidcrystal instillation, the liquid crystal inside the liquid crystaldisplay panel can be rapidly and substantially evenly dispersed.Although drops of liquid crystal fluid disperse in a circular shape whenattaching the substrates, if liquid crystal is dropped so that thedistances for dispersion between the adjacent drops of fluid aresubstantially the same, interference among the adjacent drops of fluidis minimized and the rectangular-shape area decided by the frame-shapeof the sealing material can be densely filled up with circular-shapedrops of liquid crystal fluid. Further, if an area where dispersion ofliquid crystal is sparse in the external periphery of the droppingpositions is created, the amount of liquid crystal adequate for thatarea can be supplemented. Thus, dispersion of liquid crystal issubstantially evenly rapid in both corner portions and inside the panel,thereby preventing occurrences of defects as in the past.

Next, a liquid crystal display according to a thirteenth embodiment ofthe present invention is described with reference to FIG. 57 throughFIG. 60. This embodiment relates to a fabrication method of a liquidcrystal display according to the instilling method and is specificallypreferable to be used in a fabrication method of an MVA type liquidcrystal panel. First, an instillation according to this embodiment isbriefly described with reference to FIG. 57. FIG. 57 shows a crosssection of a substrate cut vertical to the substrate surface. In thefabrication method of a liquid crystal display having processes in whichliquid crystal is dropped on one substrate (for example, TFT substrate)16, the one substrate 16 and the other substrate are attached by thesealing material made of photo-curing-type material, and the sealingmaterial is irradiated by light and cured, this embodiment shown in FIG.57 has a distinctive characteristic that liquid crystals 192 and 194 aredropped by dividing the liquid crystal instillation into more than twosessions and at the same time the components (structure, compositionratio, etc. of those liquid crystals 192 and 194 are different. In otherwords, in this embodiment, the liquid crystal 192 contacting the surfaceof an alignment film 190 under an atmospheric pressure and the liquidcrystal 194 contacting the surface of the alignment film 190 in a vacuumare made of different materials. In order to realize this, wheninstilling liquid crystal, the liquid crystal 192 higher in reliabilityis dropped on the substrate 16 and to be contacted with the alignmentfilm 190 for the first time and from the second time, the liquid crystal194 slightly inferior in reliability than the first time isoverlappingly dropped in the area (the same substrate side) where theliquid crystal 192 is dropped the first time.

Further, as shown in FIG. 58, from the third time, by dropping theliquid crystal 192 or another liquid crystal 196 higher in reliability,the liquid crystal 194 slightly inferior in reliability may be coveredby the liquid crystals 192 or 196 which are higher in reliability.

As shown in FIG. 59, the liquid crystal 192 higher in reliability may bedropped on the substrate 16 for the first time to be contacted with thealignment film 190, the liquid crystal 194 slightly inferior inreliability may be dropped in the area (the same substrate side) wherethe first dropping has been performed and then the liquid crystal 192 or196 high in reliability may be dropped in the corresponding area on anopposite substrate 31 facing the substrate 16 and attach.

Here, the reliability of liquid crystal relates to a characteristicvalue (physical property value) owned by the liquid crystal materialand, generally the following relationship is established. In otherwords, the resistivity of the liquid crystals 192 and 196 higher inreliability is higher than that of the liquid crystal 194 slightlyinferior in reliability, and the liquid crystals 192 and 196 higher inreliability fulfills the requirement of resistivity equal to be morethan 10¹⁴Ω·cm. Further, the absolute value (|Δε₁₉₂| or |Δε₁₉₆|) ofdielectric anisotropy for the liquid crystals 192 and 196 higher inreliability is desired to be smaller than the absolute value ofdielectric anisotropy for the liquid crystal 194 slightly inferior inreliability is desirable. The average dielectric constant ε₁₉₂ and ε₁₉₆[average dielectric constant: ε=(2ε⊥+ε//)/3] of the liquid crystals 192and 196 higher in reliability are desired to be less than 5.

As an example distinctly differentiating the reliabilities of the twoliquid crystals, for example in FIG. 59, a neutral material (neutralcomponent) having no strong polar group may be dropped as the liquidcrystals 192 and 196 higher in reliability and a liquid material (P-typeN-type material) having a polar group of fluorine and the like may bedropped as the liquid crystal 194 slightly inferior in reliability.

Further, by dropping the second liquid crystal 194 on the first liquidcrystal 192 previously dropped, it is required that the liquid crystal192 does not contact with the surface of the alignment film under theatmospheric pressure. So, the surface tension of the liquid crystals 192and 196 higher in reliability is desired to be smaller than the surfacetension of the liquid crystal 194 slightly less in reliability.

In the above fabrication method of the liquid crystal display, dependingon the dropping position of the liquid crystal inside the surface of thesubstrate 16, the liquid crystal to be dropped may be in differentstructure and component composition ratio. FIG. 60 shows an uppersurface of the substrate 16 where liquid crystal is dropped. A mark ◯ inthe diagram indicates the dropping position of liquid crystal. Withrespect to a mark ◯ with diagonal hatching, the plain mark ◯ indicatesthe dropping position of the liquid crystal having a higher ratio ofliquid crystal low in reliability and a mark ◯ with vertical andhorizontal hatchings indicate the dropping position of the liquidcrystal having a higher ratio of liquid crystal high in reliability. Asshown in FIG. 60, the liquid crystal at the dropping position of liquidcrystal close to the main seal 6 for attaching the two substrates hashigh ratio of the liquid crystals 192 and 196 higher in reliability thanthe center portion of the substrate. This is because if the positionsliquid crystal is dropped contacts with the main seal 6 or is irradiatedby UV, the liquid crystal having high resistance against the above isrequired.

Furthermore, in the above liquid crystal display, an anneal treatment bythe heat treatment and leveling of the liquid crystal layer by the flowof the liquid crystal layer may be performed. This is because if theliquid crystal materials are partially different in the liquid crystallayer area, optical characteristics is scattered and displayirregularities occur. The above fabrication method is preferable to beused in a fabrication method for an MVA-mode liquid crystal displayusing a vertical alignment film and N-type liquid crystal material andhaving a bank-like or protrusion-type structure on the substrate.

Next, a fabrication method of a liquid crystal display according to thisembodiment is described using examples.

Example 1

Glass substrates A and B equal to 50 (mm) in length, 60 (mm) in widthand 0.7 (mm) in thickness, forming an electrode X, electrode Y andelectrode Z which is equal to 1 cm² in electrode area are prepared byusing ITO (indium tin oxide) which is a transparent electrode material.By coating a bank-like material S1808 (resist) on the opposing surfacesof the substrates A and B and patterning, a protrusion is formed. Afteran ashing treatment, an alignment film JALS-684 (made by JSR) is formedon both substrates A and B. An UV sealing material (made by KyoritsuKagaku) is coated on the substrate A and a spacer (micropearl SP-204:4.0 μm) is dispersed on the substrate B.

By using the instilling equipment, the liquid crystal equal to Δε=−2.1is dropped only on the electrode Y on the substrate A side. Sequentiallythe liquid crystal equal to Δε=−3.8 is dropped on the electrodes X, Yand Z on the substrate A side, then a UV light equal to 60 mW/cm² inirradiation energy is irradiated to the main seal and the substrates Aand B are attached. Then, a polarizing plate is arranged in cross-nicoland an MVA-mode liquid crystal cell is completed. By applying a voltageequal to 3.5V to the liquid crystal cell, display irregularities at ahalf tone are confirmed. As a result, while there are drop-mark shapedirregularities at the electrodes X and Z, an excellent alignment statewithout irregularities are confirmed at the electrode Y portion wheredropping is performed twice.

Example 2

Using the glass substrate of Example 1, a dropped liquid crystal cell isfabricated by forming banks, protrusions, alignment film, seal coating,UV irradiation and spacer dispersion in a similar manner. Neutral liquidcrystal having Δε=0 is dropped only on the electrode Y on the substrateA side. Sequentially liquid crystal having Δ∈=−4.5 is dropped on theelectrodes X, Y and Z on the substrate A side, then UV light equal to 60mW/cm² in irradiation energy is irradiated to the main seal and thesubstrates A and B are attached. A polarizing plate is arranged incross-nicol with respect to these substrates and an MVA-mode liquidcrystal cell is completed. After attachment, the liquid crystal cell issufficiently annealed and uniformly composed therein by performing anultrasonic treatment. By applying a voltage equal to 3.5V to the liquidcrystal cell, display irregularities at a half tone are confirmed. As aresult, while drop-mark shaped irregularities exist at the electrodes Xand Z, excellent alignment state without irregularities is confirmed atthe electrode Y portion where dropping is performed twice.

As described above, by using the fabrication of the liquid crystaldisplay according to this embodiment, display irregularities at theinstillation panel can be improved and the display quality of a liquidcrystal panel can be improved.

A liquid crystal display and a fabrication method thereof according to afourteenth embodiment of the present invention is described withreference to FIG. 61 through FIG. 66. Usually, liquid crystal is droppedat a plurality of positions of the panel by a dispenser. The droppedliquid crystal 22, as shown in FIG. 61, spreads in a concentric circularshape from a dropping point 198 as time passes. As shown in FIG. 112,spreading front end portions of a plurality of dropped liquid crystaloverlap with each other and form a corrugated shape. Thus, arrival ofthe liquid crystal is delayed in comparison with other portions at thecorner portions of the main seal which is formed in a rectangularframe-shape, thus resulting in a vacuum air bubbles to be remained or arequirement of a long period of time for liquid crystal to completelyspread. If a long period of time is spent for spreading liquid crystal,the time the sealing material and liquid crystal contact is alsoextended, thereby easily generating a contamination of liquid crystal.

So, in this embodiment, a protrusion is provided on the substrate tocontrol the spreading speed of liquid crystal. By distributing liquidcrystal at a predetermined arrangement density and an arrangement shapeon the substrate where the protrusion is formed, the spreading speed anddirection of liquid crystal is controlled. Further, a column-shapespacer provided to obtain a predetermined cell gap can be applied as aprotrusion to control the spreading speed.

Although dropped liquid crystal evenly spreads in all directions on thesubstrate, if liquid crystal contacts with the protrusion, spreadingfront end portions of liquid crystal spread by wraparounding theprotrusion. Therefore, the spreading speed in the direction where theprotrusion exists is relatively slower than the direction where aprotrusion does not exist. Therefore, by arranging a plurality ofprotrusions on the substrate at a predetermined distribution density anda distribution shape, the spreading shape of the spreading front endportions of liquid crystal which is dropped on the substrate can becontrolled.

FIG. 62 shows a pixel formed on the liquid crystal display panel andspreading state of liquid crystal which is dropped on the pixel. Liquidcrystal is assumed to be dropped in substantially the center of thepixel electrode having an elongated rectangular shape in the diagram. Arelatively long structure 250 a is formed at the center of the long sideand along the long side of the external shape of the pixel electrode 14and a relatively short structure 250 b is formed at the center of theshort side and along the short side of the external shape of the pixelelectrode 14 in the external periphery of the pixel electrode 14. Nostructure is formed in a direction of a diagonal line in the pixelelectrode 14. By providing such structures 250 a and 250 b, thespreading speed of the dropped liquid crystal 22 to each portion isfaster in the diagonal direction in comparison with the vertical andhorizontal directions. So, the outline shape of front end portions ofthe spreading liquid crystal changes from a circular shape to a squareshape. Therefore, as shown in FIG. 63, by arranging the structures 250 aand 250 b in the whole panel, the outline shape of the front endportions of the spreading liquid crystal can be substantially similarfigures to the shape of the frame-shape main seal 6. Further, if thearrangement shape and density of the structure are controlled, spreadingspeed can be also controlled. Furthermore, spacers such as beads and thelike can be used by replacing the structure 252 with the predeterminedcell gap.

According to this embodiment, the direction and speed of liquid crystalto spread can be controlled and the liquid crystal can be spread alongthe shape of the main seal. Thus, the yield can be improved by reducingthe generation of vacuum bubbles remained in the corner portions of themain seal, thereby fabricating a liquid crystal display panel having ahigh attaching accuracy at a low cost. A liquid crystal display and afabrication method thereof according to this embodiment are describedbelow with reference to examples.

Example 1

A structure is formed on the CF substrate. The structure is formed byoverlaying color plates. Further, two kinds of structures are formed.One is a structure 252, as shown in FIG. 64, to define a cell gap andthe others are structures 250 a and 250 b, as shown in FIG. 65, tocontrol spreading of liquid crystal. The structure 252 to define thecell gap is formed on the whole surface of the substrate 4. On the otherhand, the structures 250 a and 250 b to control spreading of liquidcrystal, as shown in FIG. 66, are arranged adjacent to the seal. In thisexample, the structures 250 a and 250 b are provided in the internalperiphery of the main seal 6 a width of approximately 1/10 of the longside of the main seal in the horizontal direction of the main seal 6,and a width of approximately 1/10 of the short side of the main seal inthe vertical direction of the main seal 6.

It will be noted that the density of the structure 252 defining the cellgap may be reduced depending on the accuracy of the cell gap. Afterliquid crystal is dropped, the two substrates are attached under adecompressed circumstance. When the circumstance is restored to thepressurized state (atmospheric pressure), the liquid crystal spreads.However, in the center portion of the panel where the structure 252defining the cell gap exists, the dropped liquid crystal spreads in aconcentric circular shape having the dropping point as a center. Whenthe liquid crystal reaches the area where the structures 250 a and 250 bcontrolling the spreading of liquid crystal exist, the direction of thespreading liquid crystal is controlled by the structures 250 a and 250 band the spreading becomes easy in the diagonal direction of the pixels.Therefore, the outline shape of the spreading front end portions changefrom the concentric circular shape to a square shape while spreading,and lastly the liquid crystal spreads having substantially the sameshape as the main seal 6. As a result, since a time to reach the mainseal 6 is substantially the same at each area of the main seal, thegeneration of the vacuum bubbles at corner portions can be suppressed.

According to this embodiment, liquid crystal can be evenly spread and apanel in which vacuum bubbles do not remain in corner portions of theseal can be fabricated with high yield.

Further, in the above fabrication method of the liquid crystal display,the arrangement density and arrangement shape of the structures can bealso controlled so that the spreading speed in which the spreading frontend portions of the dropped liquid crystal do not contact with the mainseal 6 immediately after pressurized state is restored. It will be notedthat when a first dummy seal 6 and a second dummy seal 8 are formed inthe external periphery of the main seal 6, a vacuum area is formedbetween the first dummy seal 6 and the second dummy seal 8 whenpressurized after the substrates are attached. At this time, thedistance between the spreading front end portions of the dropped liquidcrystal and the main seal 6 is the same as or more than the widthbetween the first dummy seal 6 and the second dummy seal 8.

Next, a fabrication method of a liquid crystal display according to afifteenth embodiment of the present invention is described. An object ofthis embodiment is to steadily perform a liquid crystal instillation inthe cell process by reducing substrate deformations and display defects.In this embodiment, a fabrication method of a liquid crystal displayhaving a distinctive characteristic in holding method of the glasssubstrate in a vacuum in order to realize the above object is described.

FIGS. 67 a through 67 d show cross section cut vertically to the liquidcrystal panel, and a liquid crystal instillation, a substrate attachmentprocess and a substrate maintaining operation when attaching thesubstrates according to this embodiment is described with reference toFIGS. 67 a through 67 d. First, in FIG. 67 a, the array substrate 16 ismounted on a parallel surface plate 256. The frame-shape sealingmaterial 6 has been already formed on the array substrate 16 and liquidcrystal 184 is further dropped on the surface of the array substrate 16by instillation. In this example, the sealing material 6 is coated byapproximately 20 μm in thickness. The dropping amount of liquid crystalinside the frame-shape sealing material 6 by a dispenser is determinedby taking the thickness of a cell into consideration after the liquidcrystal display panel is attached. For example, if lengths of thevertical and horizontal sides of the internal wall of the frame-shapesealing material 6 are equal to 187.4 mm×247.7 mm, the dropping amountof liquid crystal is equal to approximately 280 ml.

The liquid crystal instillation is performed in an atmosphere. Anelectrostatic chuck 264 which does not operate in an atmosphere isprovided on the upper surface of the parallel surface plate 256, and thearray substrate 16 on the parallel surface plate 256 is mounted on theparallel surface plate 256 by a positioning pin (not shown in thediagram) and the like.

The CF substrate 4 mounted on a parallel surface plate 258 and held by amechanical holding device 260 directly opposes the array substrate 16mounted on the parallel surface plate 256 apart by a predetermineddistance. Although an electrostatic chuck 262 is provided on the uppersurface of the parallel surface plate 258, the electrostatic chuck 262does not operate in an atmosphere. Therefore, the CF substrate 4 on theparallel surface plate 258 is held by the mechanical holding device 260.Spacers 254 dispersing a plurality of beads are previously attached onthe substrate 4 surface. The spacer 254 may certainly form a pluralityof column shaped member with a predetermined height from the CFsubstrate 4 surface in place of dispersing beads.

Next, the pressure of an environment is reduced from the above state toapproximately 5×10⁻³ torr. After performing a predetermined pressurereduction, the electrostatic chuck 264 on the upper surface of theparallel surface plate 256 is operated, and the array substrate 16 isfixed on the parallel surface plate 256 by an electrostatic attraction.Further, in a similar manner, the electrostatic chuck 262 on the uppersurface of the parallel surface plate 258 is operated and the CFsubstrate 4 is fixed on the parallel surface plate 258 by theelectrostatic attraction. By the above operations, deformations such asa curvature, deflection or the like of the substrate are removed fromthe array substrate 16 and the CF substrate 4, and at the same time thearray substrate 16 and the CF substrate 4 are securely fixed on thesurface plates respectively so that a displacement of substrates and thelike do not occur when the substrates are attached in the next process.Furthermore, the operations of the electrostatic chucks 262 and 264 canbe started if the pressure of the environment is in a stable conditionless than 1×10⁻¹ torr and an electric discharge between a circuitelement such as TFT and the like formed on the array substrate 16 andgas in the environment does not occur.

Next, after an alignment of the array substrate 16 and the CF substrate4 are performed, as shown in FIG. 67 b, the two parallel surface plates256 and 258 are brought closer and the attachment of the array substrate16 and the CF substrate 4 is performed. A load at the time of attachmentof the substrates is equal to approximately 150 kgf.

Next, as shown in FIG. 67 c, by releasing the attraction due to theelectrostatic chuck, the CF substrate 4 is released from the parallelsurface plate 258 and the pressure of the environment is restored to theatmospheric pressure. Thus, the opposite array substrate 16 and the CFsubstrate 4 are further pressurized by the atmospheric pressure via thesealing material 6, liquid crystal 184 and spacers 254, therebyobtaining a uniform cell gap and at the same time uniformly spreadingthe liquid crystal 184 inside the sealing material 6 as well.

Then, as shown in FIG. 67 d, by performing, for example, an UV(ultraviolet light) irradiation 266 to the sealing material made ofphoto-curing-type resin, the sealing material 6 is cured.

As described above, according to the fabrication method of the liquidcrystal display including the substrate holding method according to thisembodiment, a substrate can be securely held on a parallel surface plateeven at the degree of vacuum less than 10⁻¹ torr. Therefore, thefabrication method according to this embodiment is extremely effectiveto be used in an instillation process on the premise that substrates areto be attached in a vacuum. Further, since the pressure at the time ofsubstrate attachment can be sufficiently increased, the substrates canbe uniformly attached. Furthermore, generation of the air bubbles in aliquid crystal layer inside the liquid crystal display panel can beprevented. Thus, the liquid crystal display panel superior in attachmentaccuracy can be fabricated at a low cost.

Next, a liquid crystal display and a fabrication method thereofaccording to a sixteenth embodiment of the present invention aredescribed with reference to FIGS. 68 a and 68 b. An object of thisembodiment is to steadily perform liquid crystal instillation in thecell process by reducing substrate deformations and display defectswhich can be produced due to the electrostatic chuck used in thefifteenth embodiment. In this embodiment, a fabrication method of aliquid crystal display having a distinctive characteristic in a holdingmethod of a glass substrate in a vacuum in order to realize the aboveobjects is described.

FIGS. 68 a and 68 b are diagrams describing an attachment of substratesby an electrostatic chuck according to this embodiment. FIG. 68 a shows,as an example, a plan view of a glass substrate 268 structured by twoarray substrates 16 and 16′ when the glass substrate 268 iselectrostatically attracted by electrostatic chucks 272 through 278.FIG. 68 b shows a cross section cut at a line A-A shown in FIG. 68 aviewed toward the cross section when the array substrate 16 and the CFsubstrate 4 are attached.

As shown in FIGS. 68 a and 68 b, two conductive paths 292 and 294electrically connecting both array substrates 16 and 16′ are formed atan area between the areas to be the array substrate 16 and 16′(hereinafter, abbreviated as array substrate 16 and 16′) which is atwo-panel formation area formed in parallel on the glass substrate 268.It will be noted that although the conductive paths are provided at twoplaces in this embodiment, this is not limited to this and theconductive paths can be provided in one place or more than three places.The electrostatic chuck for electrostatically attracting the glasssubstrate 268 has four electrodes 272, 274, 276 and 278 on the parallelsurface plate. Among the four electrodes 272 through 278, the electrodes272 and 276 structure positive electrodes and the electrode 274 and 278structure negative electrodes. A power source 288 is connected betweenthe positive electrodes 272 and 276 and the negative electrodes 274 and278. By an applied voltage from the power source 288, the surface of onearray substrate 16 is electrostatically attracted by the positiveelectrodes 272 and 276, and the surface of the other array substrate 16′is electrostatically attracted by the negative electrodes 274 and 278.An air gap is provided between boundaries of each electrode 272 through278. Although illustration of the plan view is omitted, theelectrostatic chuck of the glass substrate on the CF substrate 4 sidealso has the similar structure to the above structure on the arraysubstrate 16 and 16′ side, in which positive electrodes 280 and 284,negative electrodes 282 and 286 (illustration omitted), and a powersource 290 to apply voltage to the above electrodes are provided.

Further, the conductive paths (not shown in the diagram) electricallyconnecting the two CF substrates 4 is also formed, in the similar mannerto the glass substrate 268 on the glass substrate 270 which is a panelformation area and a plurality of areas to be the CF substrates 4(hereinafter, abbreviated as a CF substrate 4), are formed.Particularly, since a common electrode which is a conductive film on theCF substrate 4 side is formed only in the display area in order toprevent the display defects caused by a reduction in adhesive strengthof a sealing material or a shortage, usually the CF substrates 4 areelectrically separated. Therefore, if the whole substrate surface iselectrically conducted by providing a line-shape conductive path betweenthe CF substrates 4, the substrate attraction can also accomplished byapplying a voltage of the same polarity to one of the CF substrates 4.

By mounting a glass substrate on which a conductive film is formed andapplying a voltage between the electrode and the conductive film, and bygenerating the coulomb's force between the glass and the conductivefilm, the glass substrate can be attracted on electrostatic chucks ofsuch a structure. In the case shown in FIGS. 68 a and 68 b, theconductive film on the glass substrate 268 is composed of pixelelectrodes formed on the array substrate 16 and 16′, gate wirings, datawirings and the like. Further, the conductive film on the glasssubstrate the CF substrates 4 is formed thereon is composed of thecommon electrode and the like.

In order to attach the array substrates 16 and 16′ and the CF substrates4 by using such electrostatic chucks, by contacting the positiveelectrodes 272 and 276 to the array substrate 16, also contacting thenegative electrodes 274 and 278 to the array substrate 16′, and applyinga predetermined voltage between the positive and negative electrodes,the glass substrate 268 is electrostatically attracted. At this time, asshown in FIGS. 68 a and 68 b, the surface of the array substrate 16 ofthe glass substrate 268 is charged with negative (−) and the surface ofthe array substrate 16′ is charged with positive (+) by the conductivepaths 292 and 294. Accordingly, since only the electric charges of thesame polarity concentrates on a single array substrate 16 or 16′, aboundary between positive charge and negative charge within a singlearray substrate 16 is not created as in the past. Therefore, sinceimpure ion in the liquid crystal is not selectively adsorbed on thealignment film, display irregularities in which the surface of theliquid crystal display panel is divided into two equal parts andbrightness becomes uneven do not occur.

Furthermore, when the glass substrate 268 forming the array substrates16 and 16′ and the glass substrate 270 forming the CF substrates 4 areattached while being held by electrostatic attraction, as shown in FIG.68 b, if a voltage of the same polarity is applied to the opposingsurfaces of the both substrates, electric charges of the same polarityconcentrate on both opposing substrates and repel to each other, therebyreducing the substrate attraction-strength by electrostatic attractionand preventing substrate deformations and contacts among the substrates.

Next, a fabrication method of a liquid crystal display according to aseventeenth embodiment of the present invention is described withreference to FIGS. 69 a and 69 b. An object of this embodiment, similarto the sixteenth embodiment, is to steadily perform a liquid crystalinstillation in the cell process by reducing substrate deformations anddisplay defects which can be caused by the electrostatic chucks used inthe fifteenth embodiment. In this embodiment, a liquid crystal displayhaving a distinctive characteristic in a holding method of the glasssubstrate in a vacuum is described. FIGS. 69 a and 69 b are diagramsdescribing an attachment of substrates with the use of electrostaticchucks according to this embodiment. FIG. 69 a shows, as an example, aplan view in which the glass substrate 268 structured by two arraysubstrates 16 and 16′ is electrostatically attracted by electrostaticchucks. FIG. 69 b shows a structure of an electrode which includes anenlarged view of the inside the circular-shape frame of FIG. 69 a.

As shown in FIGS. 69 a and 69 b, the two array substrates 16 and 16′(panel forming area) are formed in parallel on the glass substrate 268.The electrostatic chucks for electrostatically attracting the glasssubstrate 268 have two electrode portions 296 and 297 on the parallelsurface plate. FIG. 69 b is an enlarged schematic view of the electrodeportion 296. As shown in FIG. 69 b, the electrode portion 296 of theelectrostatic chuck is formed so that the teeth of a comb-shape positiveelectrode 300 and the teeth of a comb-shape negative electrode 302 arealternating to face to each other. The positive electrode 300 and thenegative electrode 302 are connected to a power source 304. By applyinga voltage to a circuit from the positive electrode 300 to the negativeelectrode 302 via the surface of the array substrate 16, the surface ofthe array substrate 16 can be electrostatically attracted.

In this embodiment, the space (electrode pitch) between the comb-teethshape electrodes of the positive electrode 300 and the negativeelectrode 302 is fined to be equal to approximately 100 to 1000 μm.Therefore, even if a voltage is applied between both electrodesalternating to each other at minute intervals, the boundary as is in thepast becomes fine. Thus, the fabricated liquid crystal panel can obtaina uniform display quality on the display surface.

Next, a liquid crystal display and a fabrication method thereofaccording to an eighteenth embodiment of the present invention withreference to FIGS. 70 a, 70 b, and FIG. 71. It will be noted that thestructuring elements having the same operation functions as the firstthrough seventeenth embodiments are referred by the same codes and thedescriptions are omitted. FIGS. 70 a and 70 b show a comparison betweena photo-curing process by the conventional (FIG. 70 a) instillation anda photo-curing process by an instillation according to this embodiment(FIG. 70 b). Both processes are the same from a coating of the sealingmaterial after dropping liquid crystal and vacuum exhaustion (step S1)to attaching the array substrate and the opposite substrate in an vacuumenvironment (step S2).

The attached substrates are returned in an atmosphere and the liquidcrystal inside the substrates is dispersed by a use of the atmosphericpressure in the past (step S3). In order to completely disperse theliquid crystal, the substrates are further left for several minutes(step S4). Then, a shading mask is set on the substrate so that UV lightis irradiated only to the area adjacent to the sealing material (stepS5). In order to cure the sealing material, the UV light from an UVlight source is irradiated from the color filter side through theshading mask, thereby completing the photo-curing process (step S6).

On the other hand, in this embodiment, UV light for curing the sealingmaterial is irradiated from the UV light source (step S3′) in parallelwith returning the substrates in an atmosphere and dispersing the liquidcrystal inside the substrates by the air press (step S3). This step S3′is performed during the air press in the step S3 and at the same timeuntil the liquid crystal reaches the sealing material and transfer, andthe sealing material is photo-cured by being directly irradiated the UVlight on the color filter side. After completing the air press and theUV irradiation, the substrates are left for several minutes for liquidcrystal dispersion, thereby completing the photo-curing process (steps4).

It will be noted that, with respect to the relationship of thesubstrates arrangement, the opposite substrate forming the color filterthereon is provided on the upper substrate side and the array substrateis provided on the lower substrate side in both of the conventionalexamples and this embodiment. Further, photo-curing is performed withoutfixing the substrates in the conventional example, and in thisembodiment, photo-curing is performed by fixing the lower substrate onthe parallel surface plate by vacuum chucks. As a result, in theconventional example, picture-frame irregularities occur due to pressdefects and a displacement equal to approximately 7 to 10 μm occurs dueto waviness and curvature of the substrate. In this embodiment,picture-frame irregularities do not occur and a displacement can besuppressed within 3 μm.

Next, a substrate attachment equipment used in this embodiment isdescribed with reference to FIG. 71. As shown in FIG. 71, the substrateattachment equipment has a vacuum stage 71 on which a plurality ofvacuum attraction holes 74 for fixing the substrate by vacuum chucks areformed and a substrate pressing portion 72 which has a plane surface forpressing opposing the stage surface of the vacuum stage 71 and forms aplurality of air blow-off holes 76 for air press on the said pressingplane surface. The substrate pressing portion 72 movable vertically inthe diagram so that the opposing distance between the stage surface andthe pressing plane surface of the substrate pressing portion 72 can bevaried. It will be noted that in place of the vacuum stage 71, a stagehaving the electrostatic chucks may be certainly used as well. Further,since an UV light source 66 similar to the one described in the sixthembodiment is installed on the substrate pressing portion 72, the UVlight can be irradiated to the sealing material 6 during air press.

With the use of the above structure, the array substrate 16 is fixed onthe vacuum stage 71 by attraction using the vacuum attraction holes 74(or electrostatic chucks) and pressurized by air press by blowing theair from the air blow-off holes 76 of the substrate pressing portion 72to the surface of the opposite substrate 4. At the same time, UV lightis irradiated from the UV light source 66 and the sealing material 6 andtransfer are cured. Since the array substrate 16 is fixed in parallel onthe vacuum stage 71 according to this equipment, even if the oppositesubstrate 4 on the unfixed side has waviness or curvature, after heattreatment, the stress is released to be along the array substrate 16side, thereby minimizing a displacement. Further, since the sealingmaterial 6 is photo-cured while being pressurized by air press from theopposite substrate 4 side, the sealing material 6 is not pushed back andpress defects can be prevented.

Furthermore, according to this embodiment, the sealing material 6 andtransfer are cured by an irradiation of the UV light before the liquidcrystal 22 reaches the sealing material 6 and transfer. Therefore,contamination of the liquid crystal 22 due to contacts between theuncured sealing material 6 and the liquid crystal 22 can be prevented.Also, as in this embodiment, by making the lower substrate as the arraysubstrate 16 and the upper substrate as the opposite substrate 4 thecolor filter is formed, the color filter can be used as a shading mask.

Next, a liquid crystal display and a fabrication method thereofaccording to a nineteenth embodiment of the present invention isdescribed with reference to FIG. 72 through FIG. 78. First, afabrication method is briefly described with reference to FIG. 72 andFIG. 73. FIG. 72 is a schematic oblique view of the array substrate 16equal to 515 (mm)×404 (mm) structured by the two panels. Alignment layertreatment is performed inside the area of the two panels on the arraysubstrate 16 and a frame-shape main seal 306 is coated in the externalperiphery of each panel area. At the same time, a dummy seal 308surrounding the two main seals 306 at a predetermined air gap is coated.A heat combination-type sealing material is used for the main seal 306and the dummy seal 308.

After coating the sealing materials, the liquid crystal 22 is droppedinside the area of the two panels on the array substrate 16 byinstilling method.

Next, as shown in FIG. 73, the array substrate 16 and the CF substrate 4are attached. Adhesive spacers are previously dispersed on the CFsubstrate 4. This process is performed in a vacuum. Next, when theattached substrates are returned in an atmosphere, as the cross sectionshown in FIG. 74, the liquid crystal 22 between the attached substratesof the array substrate 16 and the CF substrate 4 is spread due to theatmospheric pressure. At this time, a vacuum area 310 is formed betweenthe main seal 306 and the dummy seal 308, as shown in FIG. 74, forces Pand P1 from the atmosphere operate according to an area on the substratein the vacuum area 310. These forces P and P1 are used for creating thegap for the main seal. By controlling the forces P and P1 from theatmosphere, a desired gap can be created. For example, when theviscosity of the main seal is high, as shown in FIG. 75, by making thearea on the substrate in the vacuum area 310 larger than the area shownin FIG. 74, a larger force P2 can be operated to create the gap. FIG. 76shows a difference of cell gaps, obtained by varying the area on thesubstrate surface in the vacuum area 310, adjacent to the center portionof the display area and the main seal. As shown in FIG. 76, by varyingthe area on the substrate surface in the vacuum area 310, the differenceof the cell gaps can be controlled.

Further, according to this embodiment, since the gap can be created bythe vacuum area 310, a conventional gap controlling material 312 made ofglass fiber and the like arranged in the main seal 306, as shown in FIG.77 a, is no longer required, thereby easily creating a gap regardless ofvariations in cell gap due to changes in size or structure of the panel.Furthermore, as shown in FIG. 77 b, instead of providing the gapcontrolling material 312 in the main seal 306, a bank material 314 fordefining the height of a gap can be previously formed adjacent to themain seal 306.

Also, as shown in FIG. 78, by installing a thermal heater plate 316 onthe substrate attachment stage and mounting the array substrate 16 onwhich the main seal 306 and the dummy seal 308 are created, attachmentwith the CF substrate 4 can be performed. In this case, since theviscosity of the sealing material is increased by heating the sealingmaterial and promoting the curing of the seal, the more heat is applied,the thicker the gap becomes. Therefore, by heating the sealing materialjust before the substrates are attached or during the time thesubstrates are attached in a vacuum, the gap creation can be controlled.

Thus, according to this embodiment, a preferable cell gap can be alsoformed by using the instilling method of liquid crystal.

A fabrication method of a liquid crystal display according to atwentieth embodiment of the present invention is described withreference to FIG. 79 through FIG. 87. This embodiment relates to afabrication method of a liquid crystal display by the instilling method.When vacuum bubbles are left in the sealing material in the liquidcrystal instillation process, liquid crystal leaks after attaching thesubstrates and the vacuum bubbles remain in the panel display, therebyresulting in display irregularities. Further, if a sealing material witha low to mid-viscosity (80,000 to 400,000 cps) is used, the sealingmaterial is separated from the substrate before being cured and theliquid crystal may leak out from the separated portion, therebyresulting in display irregularities. Furthermore, if a cell gap iscreated thick due to an excessive amount of the dropped liquid crystal,the surface of the panel end is shaved and an excess of liquid crystalis extracted, thereby obtaining a uniform cell gap. However, a problemof a cost increase can not be avoided.

In this embodiment, in order to solve the above problems, a main seal isformed in the periphery of the panel area, a first dummy seal is formedby surrounding the main seal with a predetermined air gap, and liquidcrystal is dropped both inside the main seal and the air gap.

According to this embodiment, display irregularities at instillation canbe minimized, a problem of a seal peeling caused by the viscosity of asealing material and the like can be further eliminated, thereby toeasily selecting a material and at the same time easily controlling acell gap.

A fabrication method of a liquid crystal display according to thisembodiment is described using examples below.

Example 1

A CF substrate and a TFT substrate which are performed an alignmentlayer treatment thereon and equal to 515 mm×404 mm are used. As shown inFIG. 79, a first dummy seal 324 is formed by coating aheat-combination-type sealing material so that the dummy seal 224surrounds a main seal 322 on a TFT substrate 320. Further, a seconddummy seal 326 is also formed by coating the heat-combination-typesealing material in the external periphery of the first dummy seal aswell.

Next, as shown in FIG. 80, liquid crystal 328 is dropped inside the mainseal 322 and in the area between the main seal 322 and the first dummyseal 324.

Next, as shown in FIG. 81, adhesive spacers (not shown in the diagram)are dispersed on a CF substrate 330 and the CF substrate 330 and the TFTsubstrate 320 are attached in a vacuum. Then the substrates are returnedin an atmosphere and at the same time a gap is created.

At this time, if a notch 332 and the like are generated in a part of themain seal 322 as shown in FIG. 82 b, liquid crystal flows out of themain seal 322 through the notch 332 and a vacuum bubble 334 entersinside the main seal 322, thereby resulting in generating displayirregularities.

In this example, as shown in FIG. 82 a, the notch 332 is intentionallyprovided in a part of the main seal 322 so that the liquid crystal 328leaks out of the main seal 322. However, since the liquid crystal 328 isin between the main seal 322 and the first dummy seal 324, a vacuumbubble does not enter inside the main seal 322 and displayirregularities do not occur.

Example 2

Using the TFT substrate 320 of Example 1 and keeping an area between thefirst dummy seal 324 and the second dummy seal 326 as an air gap, theTFT substrate 320 and the CF substrate 330 are attached as shown in FIG.83. Adhesive spacers are previously dispersed on the CF substrate 330.This process is performed in a vacuum. Next, when the attachedsubstrates are returned in an atmosphere, the liquid crystal 328 betweenthe attached TFT substrate 320 and the CF substrate 330 is spread due tothe atmospheric pressure as in a cross sectional view shown in FIG. 83.At this time, since a vacuum area is formed between the first dummy seal324 and the second dummy seal 326, forces P and P1 from the atmosphereare operated, as shown in FIG. 83, according to an expanse of the vacuumarea on the substrates. These forces P and P1 are utilized to create agap in the main seal 322. By controlling the forces P and P1 from theatmosphere, a desired gap can be created.

Example 3

The main seal 322 is formed by a sealing material with low tomid-viscosity (80,000 to 400,000 cps) and the first dummy seal 324 andthe second dummy seal 326 are formed by a sealing material with highviscosity and strong adhesion. Although when the main seal 322 and thefirst and a second dummy seals 324 and 326 are formed by the sealingmaterial with low to mid-viscosity, a seal peeling and a leakage ofliquid crystal are generated. By using the sealing material with strongadhesion for the first and second dummy seals 324 and 326, displayirregularities due to a leakage of liquid crystal and the like do notoccur although a seal peeling of the main seal 322 may be generated.

Example 4

As shown in FIG. 84, the notch 332 is formed in a part of the main seal322. The first dummy seal 324 is coated in the external periphery of themain seal 322. Liquid crystal is dropped in the whole area inside thefirst dummy seal 324, and the CF substrate and the TFT substrate areattached in a vacuum. After a gap is determined along with the releaseof atmosphere, the substrates are put in the oven at 120° C. forperforming a full curing of the sealing material and the seal iscompletely cured. At this time, the dell gap inside the panel display isformed to be 0.4 μm thinner than the intended thickness.

Then, by using a pressurization jig 336 shown in FIG. 85, the areabetween the main seal 322 and the first dummy seal 324 is pressurized bythe pressure of 0.3 kg/cm² for 10 hours. Owing to this pressurization,the liquid crystal 328 between the main seal 322 and the first dummyseal 324, as shown by arrows in FIG. 86, flows into inside the main seal322 through the notch 332 of the main seal 322, and a predetermined cellgap can be obtained.

On the other hand, when the cell gap inside the panel display is thickerthan the intended value, inside the main seal 322 is pressurized by thepressurization jig 336. By this pressurization, the liquid crystal 328inside the main seal 322, as shown by the arrow in FIG. 87, flows out ofthe main seal 322 through the notch 332 of the main seal 322 and apredetermined cell gap can be obtained.

As described above, according to this embodiment, display irregularitiesat instillation can be minimized and the yield can be improved.

Next, a liquid crystal display and a fabrication method thereofaccording to a twenty-first embodiment of the present invention aredescribed with reference to FIGS. 88 a and 88 b. In this embodiment, aliquid crystal display which can suppress irregularities in cell gapeven if the amount of liquid crystal drops at instillation in the cellprocess is not accurate is described. FIGS. 88 a and 88 b are diagramsdescribing an attachment according to this embodiment. FIG. 88 a is across section cut vertically to the surface of a liquid crystal paneland shows an intermediate state of substrate attachment. FIG. 88 b is across section cut vertically to the surface of a liquid crystal paneland shows a completed state of substrate attachment. In the diagram, thestructuring members having the same functional operations as thestructuring members previously described are referred by the same codespreviously used and the descriptions are omitted.

As shown in FIGS. 88 a and 88 b, on the array substrate 16, aconvex-type structure 298 for defining a cell gap is provided in frameshape inside the sealing material 6 and outside the display area 10.Further, on the CF substrate 4, a convex-type structure 300 for defininga cell gap is also provided in frame shape inside the sealing material 6and outside the display area 10 and at the same time at a positionfacing the convex-type structure 298 on the array substrate 16.

A liquid crystal 184 which is more than the amount required to fillinside the display area 10 and at the same time also less than theamount required to fill inside the sealing material 6 is dropped insidethe convex-type structure 298 on the array substrate 16. Then, substrateattachment is performed by the method which is previously described.First, as shown in FIG. 88 a, the array substrate 16 and the CFsubstrate 4 are brought closer together and the front end portion of thesealing material 6 on the array substrate 16 side contacts with the CFsubstrate 4. Although both of the substrates 4 and 16 are furtherbrought closer together by pressurization, at this intermediate point ofsubstrate attachment, space between the convex-type structures 298 and300 still exists, and therefore excess liquid crystal 184′ overflowingfrom the display area 10 is drained to an air gap 94 in a gap portion 93between the sealing material 6 and the convex-type structures 298 and300.

In a state in which substrate attachment is completed as shown in FIG.88 b, both of the front end portions of the convex-type structures 298and 300 are closely adhered, and a predetermined cell gap is decided bythe sum of the heights of both structures. At the same time, drainage ofthe excess liquid crystal 184′ is also prevented. Even if the air gap 94exists in the gap portion 93 to some degree, since the gap portion 93 isoutside the display area, a problem does not occur. It will be notedthat although the convex-type structures 298 and 300 are formed on bothof the array substrate 16 and the CF substrate 4 in this embodiment,this is not limited to this. A convex-type structure with apredetermined height may certainly be provided on only the arraysubstrate 16 side or only the CF substrate 4 side.

As described above, according to this embodiment, even if the droppingamount of liquid crystal varies, since the excess liquid crystal 184′ isdrained between the sealing material 6 and the convex-type structures298 and 300, the array substrate 16 and the CF substrate 4 arepressurized toward each other by the heights of the convex-typestructures 298 and 300. Accordingly, a cell gap is defined by theheights of the convex-type structures 298 and 300. Therefore, a problemin which a cell gap varies depending on the dropping amount of liquidcrystal as in the past does not occur. In other words, even if theamount of liquid crystal drops is not accurate, irregularities in cellgap can be suppressed.

Next, a liquid crystal display and a fabrication method thereofaccording to a twenty-second embodiment of the present invention aredescribed with reference to FIG. 89. In this embodiment similarly to thesixth embodiment, a liquid crystal display in which irregularities incell gap can be suppressed even if the dropping amount of liquid crystalat instillation in the cell process is not accurate is described. In thediagram, the structuring members having the same functional operationsas the structuring members previously described are referred by the samecodes previously used and the descriptions are omitted.

As shown in FIG. 89, in the display panel according to this embodiment,the sealing material has a double structure in which an inner sealingmaterial is the rectangular frame-shape sealing material 6 as shown inFIGS. 1 a and 1 b and the like and another rectangular frame-shapesealing material 340 is formed outside the sealing material 6. Anopening portion 342 is provided inside the sealing material by cuttingout a portion of the sealing material 340 so that liquid crystal canflow out.

By liquid crystal instillation process, liquid crystal more than theamount required to fill inside the sealing material 6 but less than theamount to fill inside the sealing material 340 is dropped. Then, bothsubstrates are pressurized and attached. At this time, liquid crystalwhich becomes an excess inside the sealing material 6 flows out from theopening portion 342 of the sealing material 6 to an area between thesealing material 6 and the sealing material 340.

As described above, according to this embodiment, even if the droppingamount of liquid crystal varies, since an excess liquid crystal isdrained between the sealing material 6 and the sealing material 340, aproblem in which a cell gap varies depending on the dropping amount ofliquid crystal is not accurate, irregularities in cell gap can besuppressed.

Further, in this embodiment, the opening portion 342 of the sealingmaterial 6 is provided on a side portion 344 where a TFT terminalportion 2 is not formed. Since the substrates are cut in the areabetween the sealing material 6 and the sealing material 340 after thesubstrates are attached, the opening portion 342 is required to besealed after the substrates are cut. If the opening portion 342 isprovided on a side portion of the TFT terminal portion 2 side, a plan toprevent a sealing material from flowing to a TAB (Tape AutomatedBonding) pressing area is required and the sealing process becomescomplicated. On the other hand, if the opening portion 342 is providedon the side portion 344 side where the TFT terminal portion 2 is notformed, the closing process can be simply performed.

Next, a liquid crystal display and a fabrication method thereof displayaccording to a twenty-third embodiment of the present invention aredescribed with reference to FIGS. 90 a through 90 c. In the diagram, thestructuring members having the same functional operations as thestructuring members previously described are referred by the same codespreviously used and the descriptions are omitted. First, FIG. 90 a showsan upper surface on the array substrate 16 side and FIG. 90 b shows across section cut at a line A-A of FIG. 90 a. The display area 10 isformed on the array substrate 16 and the sealing material 6 is formed inrectangular frame-shape in the periphery of the display area 10. Sixsealing materials 346-1 through 346-6 which are in a rectangularframe-shape and have a definite space inside the frame are formed in theexternal periphery of the sealing material 6.

In the liquid crystal instillation process, liquid crystal is droppedonly on the display area 10 inside the sealing material 6 and liquidcrystal is not dropped inside the frames of the sealing materials 346-1through 346-6. Then, the array substrate 16 and the CF substrate 4 (notshown in the diagram) are attached in the vacuum environment.Accordingly, since inside the frames of the sealing materials 346-1through 346-6 where liquid crystal is not dropped is attached in adecompressed state, the sealing materials 346-1 through 346-6 functionas a suction cups in an atmosphere. Thus, a displacement between bothsubstrates when the panel is released in an atmosphere after thesubstrates are attached can be certainly prevented and the accuracy ofattachment can be improved.

FIG. 90 c shows an example of a variation of the sealing material 346-1through 346-6 in which a plurality of cylindrical sealing materials 346,in place of the rectangular frame-shape shape, are provided in theexternal periphery of the sealing material 6. Since inside of thecylindrical frames of the sealing materials 346 is also attached in adecompressed state in this manner, when the substrates are returned intothe atmosphere, the sealing materials 346 function as suction cups.Thus, a displacement between both substrates when the panel is releasedin the atmosphere after the substrates are attached can be certainlyprevented and the accuracy of attachment can be improved. Shape, size,quantity, position of arrangement and the like are not limited to theexamples in FIGS. 90 a through 90 c and various shapes can be adopted.

As described above, according to the above first through twenty-thirdembodiments, problems in fabricated technology related to a liquidcrystal instillation process in the cell process can be solved and byusing the instilling method, a liquid crystal display can be fabricatedwith high yield. Accordingly, the application of the instillationprocess is realized and the cost of liquid crystal display can befurther reduced, thereby expanding the market size by replacing CRT.

Next, a liquid crystal display and a fabrication method thereofaccording to a twenty-fourth embodiment of the present invention aredescribed with reference to FIG. 91 through FIG. 94. It will be notedthat structuring elements having the same operation functions as thestructuring elements in the above embodiments are referred by the samecodes and the descriptions are omitted.

This embodiment relates to a holding method of a glass substrate in aliquid crystal instilling method and an object of this embodiment is tosimply fabricate a liquid crystal panel at a low cost by holding asubstrate on a surface plate in a vacuum.

In the instilling method, after liquid crystal is dropped on asubstrate, an array substrate and an opposite substrate are aligned andattached under a decompressed environment. However, an accuratealignment of substrates under a decompressed environment is attended bydifficulties. Further, an alignment system for aligning substrates iscomplicated and a equipment tends to be large.

In this embodiment, protrusions are provided on substrates so that whensubstrates are attached, an accurate alignment can be easilyaccomplished based on the protrusions formed on both substrates.

Structures of the substrates in a liquid crystal display according tothis embodiment are briefly described with reference to FIG. 91. Asshown in FIG. 91, sealing materials 6 and 7 are double-coated on thearray substrate 16. A protruding portion 96 having a predeterminedheight from the substrate surface is formed in frame shape in the areabetween the sealing material 6 and the sealing material 7. Further, theliquid crystal 22 is dropped at a plurality of points inside the displayarea on the array substrate 16 by a liquid crystal instilling equipmentwhich is omitted in the diagram. On the other hand, a frame-shapeprotruding portion 98 is also formed on the opposite substrate 4.

Using FIG. 92 showing a cross section cut at a line A-A of FIG. 91, theprotruding portions 96 and 98 are described in more detail. As shown inFIG. 91, the protruding portions 96 and 98 formed between the sealingmaterial 6 and sealing material 7 are formed so that, with respect tothe protruding portion 96, the protruding portion 98 is formed inward bya predetermined measurement on the substrate surface. Therefore, whenboth substrates 4 and 16 are attached after rough alignment, adifference of level of the protruding portion 98 outside of thesubstrate and a difference of level of the protruding portion 96 insideof the substrate fit together. Accordingly, the two substrates 4 and 16are accurately attached. It will be noted that sum of the height of bothprotruding portions 96 and 98 is formed higher than the cell gap of thepanel. Further, at least one protruding portion of the protrudingportions provided on the two substrates is formed so that an envelope ofa wall portion is inclined with respect to the substrate surface.

The protruding portion 98, for example, is fabricated by patterningthree color filter forming materials for forming a color filter on theopposite substrate 4 by photolithography technology and by laminatingthe three color filter forming materials in a step shape. The protrudingportion 96 is fabricated by patterning and laminating resist used in thephotolithography process when forming elements such as TFT and the likeon the array substrate 16.

FIG. 93 shows an example of a variation of the protruding portion. Asshown in FIG. 93, for example, by forming the protruding portion 96 onthe array substrate 16 side into a concave shape and the protrudingportion 98 into a convex shape on the opposite substrate 4 side and thenfitting both protruding portions together, accurate alignment can beaccomplished. It will be noted that, in this embodiment, the protrudingportion 96 is a two-parallel structure, the protruding portion 98 is tobe filled between the two parallel structures of the protruding portion96 and the protruding portions 96 and 98 are continuously provided allaround the substrates. However, this not essential and, for example,frame-shape protruding portions may certainly be formed intermittentlyalong the frame. Further, the protruding portions may certainly beprovided at four vertical and horizontal positions. In essence, aprotruding portion for deciding one position in one direction of the twosubstrates to be attached and for deciding the other position in anorthogonal direction to the other are required to be provided.Furthermore, the protruding portion 96 shown in FIG. 93 may be formedinto a conical shape of an annulus ring and the protruding portion 98into a conical shape to fit in the protruding portion 96 as a whole, andthe plurality of the protruding portions may certainly be formed on thesubstrates.

Furthermore, although double sealing materials 6 and 7 are formed in theabove embodiment, the sealing material 7 to be formed outside maycertainly be different in quality of a material from the sealingmaterial 6 inside. In this case, the sealing material 6 may be of anymaterial as long as the material has a quality which does notsubstantially change the resistance value of the liquid crystal 22. Inorder to prevent display irregularities to be generated due to areduction in voltage retention ratio of the liquid crystal, the use of amaterial in which variation of the resistance rate of the liquid crystal22 is less than 5% is desirable. Also, a material different from theinner sealing material 6 may be used as the outside sealing material 7.It will be noted that, since the double sealing materials 6 and 7 areprovided to further closely fix both substrates by having the structureof the double sealing materials function as a suction cup between thetwo attached substrates, for example, the structure may certainly be ofonly the sealing material 6.

Thus, according to this embodiment, a final alignment in substrateattachment can be decided by the position of the protrusions formed onthe substrates. If a protrusion is formed using photolithographytechnology, the accuracy of alignment equal to approximately 2 μm can beeasily realized. Therefore, an alignment can be easily and accuratelyaccomplished under a decompressed atmosphere and the size of a displaycan also be kept from being too large, thereby fabricating a liquidcrystal panel which is accurately attached without an increase in afabrication cost.

According to this embodiment, a liquid crystal display panel in whichthe accuracy of alignment is improved can be fabricated at a low cost.Further, even if the sealing materials are formed by heat-curing typematerials and the sealing materials are weakened by a heat-curingtreatment, a displacement of the substrates and the like can beprevented.

FIG. 94 shows a liquid crystal instilling equipment used in thisembodiment. A flange-shape liquid crystal scattering prevention member101 is installed in the periphery of a liquid crystal dropping hole atfront end of a liquid crystal dispenser portion 350 from which liquidcrystal is dropped. By this liquid crystal scattering prevention member101, when liquid crystal, for example, is dropped in the substratesurface of the array substrate 16, a splash of the dropped liquidcrystal can be prevented from adhering to the sealing materials 6, 7 andthe like. By obstructing a splash of liquid crystal from adhering to thesealing materials 6 and 7, the adhesion strength of the sealing materialcan be further improved.

Next, a liquid crystal display according to a twenty-fifth embodiment ofthe present invention is described with reference to FIG. 72 and FIG. 95through FIG. 100. This embodiment relates to a fabrication method of aliquid crystal display according to an instilling method. Thisembodiment has a distinctive characteristic in that after the substratesare attached by the instilling method and released in an atmosphere, thesubstrates are left on a stage with a high degree of flatness, and UVirradiation for curing the sealing material is performed under a statein which the substrates are further attracted on the stage. Byattracting and holding the substrates to the stage with a high degree offlatness, the substrate surface copies after the state surface of a highdegree of flatness, and steady curing of the sealing materials in whichdisplacement of substrates and distortion are suppressed can beobtained.

Further, if the same stage can be used for substrate mounting stageswhen releasing in an atmosphere and when irradiating UV, stabilityagainst the displacement of substrates can be further increased. If astage is changed when releasing the substrates in an atmosphere and whenirradiating UV to the substrates, by always keeping conveyance andwaiting periods of the substrates constant until UV irradiation isperformed, distortions become stabilized and displacement can becontrolled.

Examples of a fabrication method of a liquid crystal display accordingto this embodiment is described with below reference to comparativeexamples and diagrams.

Adhesive spacers or column-shape spacers made of resin are formed on oneof the array substrate which can take two 15-inch planes performed thealignment-film treatment therein and the CF substrate, and aheat-combination-type UV sealing material is coated on the other. Atthis time, by surrounding the external periphery of the main seal 306,as shown in FIG. 72, by a dummy seal 72 and forming a vacuum area 74,the substrate displacement between the array substrate 16 and the CFsubstrate 4 when attaching the substrates and substrate displacement dueto vibrations and deflection during the substrate conveyance can alwaysbe substantially constant.

Sequentially, the liquid crystal 22 is dropped on the array substrate 16and the both substrates are mounted on the stage and attached in thevacuum environment. Although then the substrates are released in anatmosphere, since the area surrounded by the main seal 306 is keptvacuum, when the liquid crystal 22 spreads in the subject area, a gapformation simultaneously begins owing to a pressure difference with theatmospheric pressure.

At this time, as a comparative example, the panel is first conveyed ontothe top of an ordinary desk and the like having a low degree offlatness, then the panel is returned on the released stage in theatmosphere and UV irradiation is performed.

On the other hand, as an example, after the panel is left on top of theordinary desk and the like similarly to the comparison example, thepanel is returned on the released stage in an atmosphere, the panel isfurther attracted by an attraction mechanism and UV irradiation isperformed.

FIG. 95 illustrates the result of the above example and comparativeexample. In FIG. 95, a scale mark represents 1 μm and the solid linewith a mark x on corner portions shows a position for attaching the CFsubstrate on the array substrate taking two 15-inch planes therein basedon the design values. In FIG. 95, the solid line with a mark Δ on cornerportions shows a displacement of attachment between the array substrateand the CF substrate according to this example. Further, the solid linewith a mark ♦ on corner portions shows a displacement of attachmentbetween the array substrate and the CF substrate according to thecomparative example. As shown in FIG. 95, while a displacement betweenthe substrates is as small as approximately 2 μm in this example, adisplacement between the substrate in the comparative example is morethan 5 μm due to a large distortion generated in the panel.

Next, as an example 2, a panel is mounted on a stage having a degree offlatness equal to ±50 μm and attached in a vacuum, the panel is leftattracted on the subject stage after releasing the panel in anatmosphere until a gap is completely created, and the sealing materialis cured by UV while the panel is still attracted on the stage. FIG. 96illustrates the result of the example 2. In FIG. 96, a scale markrepresents 1 μm, the solid line with a mark x on corner portions shows aposition for attaching the CF substrate on the array substrate takingtwo 15-inch planes therein based on the design values. In FIG. 96, thesolid line with a mark ▪ on corner portions shows a displacement ofattachment between the array substrate and the CF substrate according tothis example for the first time. The solid line with a mark Δ on cornerportions shows a displacement of attachment between the array substrateand the CF substrate according to this example for the second time. Asclear FIG. 96, according to this example, a displacement between thesubstrates can be less than 2 μm and at the same time the amount ofdisplacement between the substrates can be suppressed to a substantiallyconstant and stable amount.

On the other hand, as a comparative example 2, a panel is mounted on astage having a degree of flatness equal to ±50 μm and attached in avacuum, and the panel is carried out of the stage after releasing thepanel in an atmosphere and irradiated by UV on top of a desk. FIG. 97shows the result of the comparative example 2. In FIG. 97, a scale markrepresents 1 μm, the solid line with a mark x on corner portions shows aposition for attaching the CF substrate on the array substrate takingtwo 15-inch planes therein based on the design values. In FIG. 97, thesolid lines with marks ▪, ♦ and Δ on corner portions show displacementsof attachment between the array substrate and the CF substrate accordingto this comparative example for the first through third timesrespectively. As clear in FIG. 97, according to the comparative example2, large displacements between the substrates occur due to thedistortions generated in the panels.

Next, as shown in FIG. 98 as an example 3, taking a distortion of thepanel into consideration, the panel is supported by five pins 352 atfour corners and substantially the center under the panel for apredetermined period after releasing the panel in an atmosphere.Subsequently, the panel is again mounted on the stage used forattachment and attracted, and performed the sealing-cure by UVirradiation. The result of the example 3 is shown in FIG. 99. In FIG.99, a scale mark represents 1 μm and the solid line with a mark x oncorner portions shows a position for attaching the CF substrate on thearray substrate taking two 15-inch planes therein based on the designvalues. In FIG. 99, the solid line with a mark ▪ on corner portionsshows the result in which after the panel is supported by the pins 352for 30 seconds, the panel is mounted on a stage, attracted therein, andcured the seal by UV irradiation. The solid line with a mark Δ on cornerportions shows the result in which after the panel is supported by thepins 352 for 60 seconds, the panel is mounted on a stage, attracted, andcured the seal by UV irradiation. Further, the solid line with a mark ♦on corner portions shows the result in which the panel is mounted on astage without being supported by the pins 352, attracted, and cured theseal by UV irradiation. As clear in FIG. 99, distortions vary dependingon the period the panel is supported. If the amount of distortion is assmall, constant and stable as shown in FIG. 99, a displacement betweenthe substrates can be controlled by correcting the stage apparatus formounting the panel and the like.

FIG. 100 shows the result of consecutively fabricating five substratesin which each panel is conveyed by the similar operation to the above,the period from the time the panel is released in an atmosphere to thetime UV irradiation is performed is constant, and the panel is attractedand cured by UV. As clear in FIG. 100, the amount of displacement iscontained within a 3 μm square area at four corners of the CF substrateand can be sufficiently controlled by correcting the offset at theattachment even in the mass production process. Further, when an UV lampgenerating a UV wavelength of less than 280 nm is used, liquid crystalis degraded and display irregularities reducing the retention ratio aregenerated. However, by using a filter to cut the UV wavelength less than280 nm, a panel without display irregularities can be formed.

Thus, according to this embodiment, by using the instilling method,distortions generated in the glass substrate and a displacement betweenthe two substrates facing each other can be steadily controlled and astable fabrication process in which display irregularities do not occurand is feasible for mass production can be obtained.

Next, a fabrication method of a liquid crystal display according to atwenty-sixth embodiment of the present invention is described withreference to FIG. 101 through FIG. 103. This embodiment also relates toa fabrication method of a liquid crystal display according to theinstilling method and is particularly ideal for using in a fabricationmethod of an MVA-type liquid crystal panel. First, a structure of anactive matrix-type liquid crystal display fabricated by a fabricationmethod of a liquid crystal display according to this embodiment isbriefly described with reference to FIG. 101. FIG. 101 shows a planesurface of a substrate and equivalent circuits of the pixels viewing thearray substrate of a liquid crystal display from the liquid crystallayer side. As shown in FIG. 101, a plurality of drain bus lines 353extending vertically in the diagram are formed on the array substrate16. Further, a plurality of gate bus lines 354 which are orthogonal tothe drain bus lines 353 and extend horizontally in the diagram areformed on the array substrate 16. The areas decided by these drain buslines 353 and gate bus lines 354 are the pixel areas.

A TFT 356 is formed adjacent to the intersection of the drain bus line353 and the gate bus line 354 in each pixel area. A drain electrode 358of the TFT 356 is connected to an adjacent drain bus line 353. A sourceelectrode 360 is connected to a pixel electrode 364 formed in the pixelarea. A gate electrode 362 is connected to an adjacent gate bus line354. Further, a storage capacitor bus line 355 is formed crossing eachpixel area.

Further, one end portion of each gate bus line 354 is electricallyconnected by a gate bus line bundle wiring 366. The end portion of thegate bus line bundle wiring 366 is pulled out to the end portion of thearray substrate 16 and connected to an external connecting terminal 368.Similarly, one end portion of the drain bus line 353 is electricallyconnected by a drain bus line bundle wiring 370. The end portion of thedrain bus line bundle wiring 370 is pulled out as far as to the endportion of the array substrate 16 and connected to an externalconnecting terminal 372.

Further, one end portion of the storage capacitor bus line 355 iselectrically connected by a storage capacitor bus line bundle wiring374. Furthermore, a common electrode (not shown in the diagram) formedon the CF substrate 4 side is also connected to the storage capacitorbus line bundle wiring 374 via a transfer 378. The end portion of thestorage capacitor bus line bundle wiring 374 is pulled out to the endportion of the array substrate 16 and connected to an externalconnecting terminal 376. The external connecting terminals 368, 372 and376 are adjacent to one another and arranged in a row on the end portionof the array substrate 16 so that a signal from in an inspection deviceat the time of a panel inspection can be input. Also, the end portion ofthe external connecting terminals 368, 372, 376 arranged on the arraysubstrate 16 are formed with a shift from the end portion of the CFsubstrate 4.

These bundle wirings 366, 370 and 374 are utilized as common electrodeselectrically connecting each bus line 354 in order to protect fromstatic electricity in the fabrication process of the array substrate 16.The gate bus line bundle wiring 366 and the drain bus line bundle wiring370 among these bundle wirings 366, 370 and 374 are cut and separatedafter attaching the array substrate 16 and the CF substrate 4 andperforming the panel inspection. On the other hand, the storagecapacitor bus line bundle wiring 374 is left alone and functions tosupply common electrode potential to the storage capacitor bus line 355.

In a fabrication method of a liquid crystal display, for example, havingthe process in which liquid crystal is dropped on the array substrate16, the array substrate 16 and the CF substrate 4 are attached by asealing material made of photo-curing-type material and the sealingmaterial is irradiated by light and cured, the liquid crystal displaypanel shown in FIG. 101 can be obtained by attaching the array substrate16 and the CF substrate 4 so that the end portions of both substratesare relatively shifted and by arranging the external connectingterminals 368, 372 and 376 for panel inspection in the shifted area. Itwill be noted that by varying the sizes of the substrates for the arraysubstrate 16 and the CF substrate 4 beforehand, the external connectingterminals 368, 372 and 376 may also be arranged in an open area createdwhen both substrates are attached.

Next, an example of a panel inspection is described with reference toFIG. 102 and FIG. 103. The lateral axis in FIG. 102 represents time andthe vertical axis represents voltage. FIG. 102 shows each voltage wavewhen gate voltage (Vg) is applied from the external connecting terminal368, drain voltage (Vd) is applied from the external connecting terminal372 and common voltage (Cv) is applied from the external connectingterminal 376. The object of the panel inspection shown in FIG. 102 is toinspect irregularities in cell gap and liquid crystal instillation(uninstillation, leakage, etc.). Therefore, by fixing the common voltage(Vc) at 10V and further fixing the gate voltage (Vg) at 22V andreversing the drain voltage (Vd) at an interval equal to 16.7 ms withina range of plus or minus 1.6 through 5.0V based on the common voltage,display irregularities in the display area are detected. Displayirregularities can be detected with the visual observation orautomatically a solid image pickup element such as CCD and the like.

FIG. 103 is a graph showing the variation of transmissivity according toa difference in cell gap. In FIG. 103, the lateral axis indicates thedrain voltage Vd and the vertical axis indicates transmissivity.Further, a solid curved line in the diagram shows a case when a cell gapis equal to 4.2 μm and a dotted curved line shows a case when a cell gapis equal to 3.8 μm. Therefore, as clear in FIG. 103, by performing thepanel inspection described with reference to FIG. 102, a displayirregularity in which brightness varies depending on the distribution ofa cell gap in the panel display area can be detected.

When irregularities in liquid crystal instillation or gap creation arefound from the panel inspection on described above, the array substrate16 and the CF substrate 4 can be peeled off and recommitted to aprevious process. In a fabrication process of a liquid crystal displayusing liquid crystal instillation, since cutting of a gang printingmother glass and the like are performed at the end of the process, thearray substrate 16 and the CF substrate 4 which are peeled offrespectively keeps the same glass size as that in the previous process.In a reproducing treatment, liquid crystal is washed by a solvent suchas alcohol, acetone or the like, an alignment film and sealing materialare removed from a substrate with a use of ashing, solvent and the like,thereby resuming again from the alignment film printing process.

As described above, according to the present invention, curing defectsof a sealing material in the cell process can be reduced. Further,according to the present invention, peeling of a sealing material in thecell process can be prevented. Furthermore, according to the presentinvention, substrate deformations and display irregularities in the cellprocess can be reduced. Also, according to the present invention,variations of a cell gap which may be generated in the cell process canbe reduced. Finally, according to the present invention, liquid crystalinstillation in the cell process can be steadily performed.

As described above, according to the present invention, even if UVirradiation for curing a sealing material is performed, liquid crystalis not degraded, thereby realizing a liquid crystal display having adisplay quality with excellent picture using the instilling method.

Further, according to the present invention, a sealing material made ofa photo-curing-type material can be cured with certainty. Furthermore,according to the present invention, displacements of attached substratesoccurred when curing a sealing material can be reduced. Also, accordingto the present invention, press defects of the substrate at the time ofinstillation can be improved. Furthermore, according to the presentinvention, an enlargement of the external dimensions of a panel at thetime of instillation can be suppressed.

Therefore, according to the present invention, a liquid crystal panelwith improved yield can be fabricated by using the instilling method,thereby further reducing the fabrication cost of a liquid crystaldisplay.

As described above, according to the present invention, in a liquidcrystal display in which a frame-shape structure and a black matrixpicture frame are formed in an area between a main seal and displayarea, peeling of a sealing material can be prevented, thereby realizinga liquid crystal display in which contamination of liquid crystal due touncured sealing material can be prevented.

Further, according to the present invention, the instilling method ofliquid crystal in a fabrication process of an MVA-mode liquid crystaldisplay can be improved, thereby reducing display irregularities.Furthermore, according to the present invention, an inspection ofdisplay irregularities can be easily performed.

Also, according to the present invention, even if an instilling methodof liquid crystal is used, an excellent cell gap can be formed.

Further, according to the present invention, even if an instillingmethod is used, generation of displacements of two attached substratesand displacements due to distortions in a substrate and gapirregularities can be prevented.

1. A method of fabricating a liquid crystal display comprising: forminga main seal by depositing ultraviolet-light-curing resin at an externalperipheral portion of a display area of a substrate; forming aframe-shape structure, which shades ultraviolet light, at an areabetween the main seal and the display area; sandwiching liquid crystalby attaching the substrate and an opposing substrate; and curing themain seal by irradiating ultraviolet light from a horizontal or diagonaldirection to the substrate surface.
 2. A method of fabricating a liquidcrystal display as set forth in claim 1 wherein the curing stepcomprises mounting the substrate on a substrate stage forming aconcavo-convex structure, and reflecting ultraviolet light irradiatedfrom the diagonal direction to the main seal with the concavo-convexstructure.
 3. A method of fabricating a liquid crystal display havingprocesses of dropping liquid crystal at a plurality of positions on oneof multiple substrates, attaching the one of the substrates with theother substrate via a sealing material made of a photo-curing typematerial, and curing the sealing material by irradiating light thereoncomprising: using a polarized light in the curing process.
 4. A methodof fabricating a liquid crystal display as set forth in claim 3, whereinthe using step comprises making a polarized axis of the light to becoincident with a minor axis of molecules of the liquid crystal.
 5. Amethod of fabricating a liquid crystal display having processes ofdropping liquid crystal at a plurality of positions on one of multiplesubstrates, attaching the one of the substrates with the other substratevia a sealing material made of a photo-curing type material, and curingthe sealing material by irradiating light thereon comprising:irradiating the light after perpendicularly aligning the molecules ofthe liquid crystal adjacent to the sealing material.
 6. A method offabricating a liquid crystal display as set forth in claim 5, whereinthe irradiating step comprises perpendicularly aligning the molecules ofthe liquid crystal having a positive dielectric anisotropy and being atleast adjacent to the sealing material by applying a voltage between thesubstrates.